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Why Koi?
Koi Growth
Hummingbirds
Sexing Koi
Koi Feeding
Koi History
Koi Can Over-Heat
Koi Age
Koi CPR
Koi Taxonamy
Koi can hear
Koi Nutrification
Koi Filtration
Koi Shows
Q: Why Koi? Why should I choose Koi for my pond? A: Koi fish are a great hobby. They also help you to relax and relieve stress. Koi are particularly fun to watch eat. Although Koi will eat many natural food sources such as algae and other natural pond residents, the greatest pleasure for many Koi keepers is in feeding them. They are truly hogs. They look like piranhas at feeding time, churning the water, jumping, and I have seen some perform like porpoises, walking along the water's surface on their caudal fin. Once you hear the sucking sound of Koi sucking down food you'll never forget it. They remind me of water polo players who are about to get to the ball when suddenly other players from behind swim up and over them pushing them under the water. Koi will even swim up on lily pads to get trapped food. They are very smart, and can be trained to eat out of your hand. They are by nature bottom rooting and feeding carp. They quickly learn to eat floating dry food. The food typically runs $1 to $2 per pound. I have found floating feeding rings add to the enjoyment. They learn to "hang out" around the feeding ring. Koi are very expensive when they are full size (30 to 40" in 5 to 8 years), but as small fish they are only a few dollars each. The prices are listed on our "Koi For Sale" and "Koi Pricing" pages. Koi can live for 30 to 40 years, and even longer. Many Koi ponds can come close to breaking even by selling off the excess Koi after they have grown larger. On the other hand, an investment of $500 to $1,000 of small Koi each year for 5 years, could possibly yield 1,000 or more Koi worth more than $1,000,000. Large size Koi can easily be worth $1,000 each, great quality Koi can bring $250,000 each or more, but are rare. However, to do this you would need to have a unique resource such as a 50,000 - 200,000 gallon pond. Once you have the pond you would have an inexpensive way to raise large numbers of Koi, while enjoying them. After 3 or 4 years the Koi should start breeding themselves. One female can lay 100,000's of eggs. Of course there could, and probably would, be unknown complications to such a rosy story. There are predators about such as Great Blue Herons, Kingfishers, some snakes, raccoons, etc. However with a large pond the majority of the Koi should be able to evade, escape, and survive the predators; any hideouts or shelters would help. Natural selection would tend to favor the quick, smart, and wary Koi. There are 2 footed predators with fishing gear and nets. However, even if they could get access Koi would not be an easy catch. Any sources of water runoff feeding your pond which could contain large concentrations of insecticides, herbicides, etc. could be a serious problem. You would need to control and divert such runoff. Koi stay healthy by having a large pond to live in. Testing the water quality for ammonia, nitrites, nitrates, carbonate hardness, salinity, pH, oxygen concentration etc., is an important and frequent requirement. The water quality must be kept high. There are parasites, fungal, viral and bacterial infections to be sure, but they can be kept under control with good observation and some testing, such as microscopic examination of skin scrapings, small pieces of gill tissue, and an occasional autopsy. You may need to hire help in this area. Most remedies are used in the ppm concentration, so even large ponds are fairly reasonable to treat. Some sick Koi will require injections. Fortunately, when they get sick they are easy to catch. Koi are comfortable in water with around 0.1% salt, which is low enough not to bother most pond plants. 0.3% salt is supposed to keep most parasites under control, but that doesn't always work as well as some claim, and the higher salt concentration can play havoc with some pond plants.    Q: Koi Growth How large do Koi get? A: Some Koi can get to be a meter long which is 100 centimeters, 3.28 feet or 39.37 inches. However, modern Koi average closer to 80 centimeters (31.5 inches), which is still a long way from the 1/16th inch of the newly hatched Koi. Using the Ludwig von Bertalanffy growth equations (1938) it can be shown that generally Koi reach about 50% of their final adult length at 24 months, 95% at 10 years, and 99% at 14 years. Obviously their size depends on the environmental conditions such as pond size, oxygen concentration, water temperatures, water quality, amount and type of food, and length of the growing season. Vitamins, exercise, and lack of stress may also play an important role. In the mid 1980's in Lake Biwa in Japan they netted a 6.5 foot Cyprinus carpio, but it died in a public aquarium in Kyushu. There are other examples of carp reaching enormous sizes in large bodies of water. The mahseer, a member of the carp family Cyprinidae, genus Barbus, typically reaches 6.5 feet and a weight of 200 pounds. It is found in Southeastern Asia. Although that is a big fish, it is not as big as the wels, also called WALLER (species Silurus glanis), a large, voracious catfish of the family Siluridae, native to large rivers and lakes from central Europe to western Asia. One of the largest catfishes, as well as one of the largest of European freshwater fishes, the wels attains a length of about 4.5 m (15 feet) and a weight of 300 kg (660 pounds). Back to our favorite Koi. It appears that depending on their age and under optimum conditions Koi can grow over 2 centimeters (almost an inch) per month or faster, remember there are 2.54 cm in an inch. Check out the growth rates in the following graphs. Just click on the charts to expand them - then click on your browser's back arrow to return. Graph A shows length in cm versus age in months, shown by an empirical equation (magenta line) fit to the Koi data (blue dots) from the literature. Graph B shows length of Koi divided by age which is a rough gauge of growth rate. Graph C is of a Ludwig von Bertalanffy (1938) growth equation that shows length in centimeters and inches versus age in months and years. Again the Koi data from the literature are represented by the blue dots. This assumes a constant growing season in a temperate climate. In cold climates there would be steps notched into the upward curve during the winter non-growing season. Graph D is the 1st derivative of the above equation (Graph C) which is another measure of the rate of growth versus age. The true rate of growth in centimeters per month as a function of the Koi's age is probably somewhere between Graphs B & D, both of which show fish need to be fed well particularly during their prime growth period, when under 2 years of age. Following is a table based on the Ludwig von Bertalanffy equation: Months Inches Years Cm 0 0.3 0.0 0.7 1 1.1 0.1 2.9 2 2.0 0.2 5.0 3 2.8 0.3 7.1 4 3.6 0.3 9.1 5 4.4 0.4 11.1 6 5.1 0.5 13.0 7 5.8 0.6 14.8 8 6.5 0.7 16.6 9 7.2 0.8 18.4 10 7.9 0.8 20.1 11 8.6 0.9 21.7 12 9.2 1.0 23.3 13 9.8 1.1 24.9 14 10.4 1.2 26.4 15 11.0 1.3 27.9 16 11.5 1.3 29.3 17 12.1 1.4 30.7 18 12.6 1.5 32.1 19 13.2 1.6 33.4 20 13.7 1.7 34.7 21 14.2 1.8 36.0 22 14.6 1.8 37.2 23 15.1 1.9 38.4 24 15.6 2.0 39.5 25 16.0 2.1 40.6 26 16.4 2.2 41.7 27 16.8 2.3 42.8 28 17.2 2.3 43.8 29 17.6 2.4 44.8 30 18.0 2.5 45.8 31 18.4 2.6 46.7 32 18.8 2.7 47.6 33 19.1 2.8 48.5 34 19.4 2.8 49.4 35 19.8 2.9 50.2 36 20.1 3.0 51.1 37 20.4 3.1 51.9 38 20.7 3.2 52.6 39 21.0 3.3 53.4 40 21.3 3.3 54.1 41 21.6 3.4 54.8 42 21.9 3.5 55.5 43 22.1 3.6 56.2 44 22.4 3.7 56.9 45 22.6 3.8 57.5 46 22.9 3.8 58.1 47 23.1 3.9 58.7 48 23.4 4.0 59.3 49 23.6 4.1 59.9 50 23.8 4.2 60.4 51 24.0 4.3 61.0 52 24.2 4.3 61.5 53 24.4 4.4 62.0 54 24.6 4.5 62.5 55 24.8 4.6 63.0 56 25.0 4.7 63.5 57 25.2 4.8 63.9 58 25.3 4.8 64.4 59 25.5 4.9 64.8 60 25.7 5.0 65.2 61 25.8 5.1 65.6 62 26.0 5.2 66.0 63 26.1 5.3 66.4 64 26.3 5.3 66.8 65 26.4 5.4 67.2 66 26.6 5.5 67.5 67 26.7 5.6 67.9 68 26.8 5.7 68.2 69 27.0 5.8 68.5 70 27.1 5.8 68.8 71 27.2 5.9 69.1 72 27.3 6.0 69.4 73 27.5 6.1 69.7 74 27.6 6.2 70.0 75 27.7 6.3 70.3 76 27.8 6.3 70.6 77 27.9 6.4 70.8 78 28.0 6.5 71.1 79 28.1 6.6 71.3 80 28.2 6.7 71.6 81 28.3 6.8 71.8 82 28.4 6.8 72.0 83 28.4 6.9 72.2 84 28.5 7.0 72.5 85 28.6 7.1 72.7 86 28.7 7.2 72.9 87 28.8 7.3 73.1 88 28.8 7.3 73.3 89 28.9 7.4 73.4 90 29.0 7.5 73.6 91 29.1 7.6 73.8 92 29.1 7.7 74.0 93 29.2 7.8 74.1 94 29.3 7.8 74.3 95 29.3 7.9 74.5 96 29.4 8.0 74.6 Months Inches Years Cm We would appreciate any comments and age versus length data you can send us to make these graphs more accurate.  Q: Hummingbirds Hummingbirds? A: HUMMINGBIRDS NEED NECTAR, and the flowers, which provide the nectar, need to be pollinated. What a perfect match! A good hummingbird garden has more than just hummingbird flowers. It is a whole habitat. Q: Sexing Koi Is it difficult to tell the sex on Koi? A: It is difficult to tell the sex on younger Koi, it gets easier as they get older. Females tend to have rounder bodies and rounder pectoral fins and their fins tend to be somewhat smaller. Males are sleeker, with more pointed pectoral fins, and their fins tend to be larger. Others claim the colors of males are more brilliant. Older males have a sand paper like raspiness on the gill plates, and some claim you can also feel a roughness if you lick your tongue across the front of the pectoral fin. If you try this let us know! The easiest way is when there is a particularly aggressive male chasing the females, with the proverbial nose up the butt, you look for other males chasing the same now identified females. Q: Koi Feeding What about Koi feeding? A: Koi feeding probably leads to more Koi deaths than we care to know. Most of us overfeed our Koi. Why? Because we love them, and we want them to grow bigger and faster. "If only they would eat chicken soup". Some people say only feed them as much as they will eat in 5 minutes, then they stretch that to 10 minutes. As we feed them more and more, the waste products form more and more ammonia and nitrite, until the water becomes toxic and they die. (click here to see more about Nitrification) What we are really doing is overfeeding our filtration system. I'm not sure we can ever overfeed Koi. The most important tool we have to know when we are feeding too much is an ammonia test kit. If ammonia shows up we are most likely feeding too much (or our biological filter was damaged). As long as ammonia doesn't show up (nitrite readings follow the ammonia readings) we can feed away. Remember, the feed turns into ammonia and phosphates. Ammonia is converted to nitrites, which are then converted to nitrates. So we wind up with lots of phosphates and nitrates, which equals fertilizer, which causes algal blooms (green water). Plants will eat up some of it, and water changes will help get rid of the rest. (click here to see water change calculations) If we cut their food back to lower the ammonia, guess what happens? They start recognizing us, come over to get their food, will eat out of our hands, etc. Some people feed them spinach, bread, triscut crackers, whole peas, vitamins, watermelon rind, etc. If you want some more ideas ask some carp fishermen what they use as bait. Some have great secret formulas. We recently calculated that we were feeding 6" Koi 1 gram of food per day, or 5 pellets per feeding (4 feedings / day). Q: Koi History What is the history of Koi? A: Today Koi are bred in every country and considered to be the most popular fresh-water ornamental pond fish and are often referred to as being "living jewels" or "swimming flowers". Koi are a variety of the common carp, Cyprinus carpio. Carp fossils have been discovered in South China dating back about 20 million years. Some varieties are known for their hardiness, which records claim can live for long periods of time if simply wrapped in wet moss continuously kept damp. Some authorities believe Koi originated in Persia and spread throughout the ancient world. Koi, or nishikigoi - Japanese for "brocaded" carp - were first described in writing from a Chinese book written during the Western Chin Dynasty, 265-316 A.D. At that time they were described as white, red, black and blue. What happened to Koi from the 2nd to the 17th century is still being investigated, but many suspect Koi were gradually spread around the orient, and possibly even via trade caravans to or from the middle east. Koi breeding in Japan is recorded from the 17th century in the rice-growing region of the Niigata Prefecture. They were originally bred as protein food supplements. Q: Koi Can Over-Heat Can Koi over-heat? A: Koi make ammonia from the food they eat. Koi are sometimes referred to as ammonia machines. The reason for this is because of the quantity of food that they eat. This ammonia is made in several different ways: Koi respiration introduces ammonia through the gills Koi digestion generates ammonia through: Urine Feces Un-eaten food decomposes into several chemicals including ammonia. Sediment on the pond bottom, consisting of feces, plant material from within the pond as well as wind-blown leaves, and other dead organisms, also generates ammonia. We can calculate the ammonia generated by the food by making a few assumptions: We feed just the proper amount of food each and every day, which establishes a "Steady State" condition producing the same amount of ammonia each and every day. Once we know the weight of food we feed each day the calculation becomes easy. Koi eat about 1% to 2% of their body weight in food each and every day, but the calculation should be based on the actual weight of food we feed daily. The protein content of Koi premium pond food is typically 36%, but sometimes is as high as 40%. The nitrogen content of protein is typically 16% (the Kjeldahl Analytical Method is based on this). So multiplying the weight of the food by the % protein, and then by the % of Nitrogen in the protein, we know the weight of atomic Nitrogen going into the water. If we know the volume and thus the weight of the water, we can then calculate the ppm of nitrogen. A few calculations based on these assumptions for a typical Koi pond, show that this results in the production of 1.6 ppm of atomic nitrogen every day. This creates 1.9 ppm of ammonia (4.3 ppm for 2% food - 40% protein) 1.9 ppm of ammonia creates up to 5.2 ppm of nitrite (11.6 ppm for 2% food - 40% protein) So each day we generate 1.9 ppm of ammonia, and up to 5.2 ppm of nitrite. When we measure the amount of ammonia and nitrite actually present, we know the difference is the amount "digested" by the bacteria daily. If there are no bacteria to digest the ammonia and nitrite (see Koi Nitrification), and there are no water changes, then the ammonia concentration will increase by 1.9 ppm per day; the nitrite by up to 5.2 ppm per day. Under these conditions the Koi will soon die from the toxicity of ammonia and nitrite. A couple of weeks in water over 20 ppm of ammonia or nitrites and we will have mostly dead Koi, the ones still alive will have Columnaris and Aeromonas infections, such as hole in the side disease, fin rot, tail rot, secondary fungal infections, etc.. Q: Koi Age How can I tell a Koi's age? A: Many of us wonder, "how old is our favorite Koi"? One way to guess at the answer is to measure how long they are, and then check the Koi Growth Charts. However, most Koi have scales; thin, overlapping plates of bone that continue to grow throughout life. As they grow they do not increase in number, but rather increase in size. The growth of the scales is proportional to the Koi's growth, and annual marks are formed on the scales at the same time every year, along the outer edges. So if you look at a Koi scale, it turns out that just like trees in cross-section, they have annular rings. If your Koi has lost a scale, look at it closely, even under a microscope. Then count the number of annular rings, and your Koi is at least that old, but it maybe even older. This is more accurate for younger Koi, i.e., less than 5 years old. However, if a Koi looses a scale, and then grows it back, the new scale will not have any of the older rings. Also females may not add growth rings when they are reproducing, or grow some more after reproducing, causing 1 growth ring to look like 2. A more accurate way to judge a Koi's age is to examine the cross-section of a fin spine, which also has annular rings. The second anal fin spine is often used. This can be done without doing permanent damage, since the fin will grow back. The most accurate way to determine a dead Koi's age is to examine the Otolith (Williams and Bedford 1974). The Otolith is the Koi's "ear bone". Otoliths are part of Koi's vestibular apparatus, and reside in the cranial cavity. They are composed of calcium carbonate and protein. They function as sound receptors and are also used for balance and orientation. There are 3 pairs of otoliths or ear stones in the inner ear of a Koi. The largest pair of Otoliths, the sagittae, are routinely used for aging. So Otolith is synonymous with sagitta. Again you count the number of annular rings under a microscope. White bands are formed during the spring and summer months, while darker bands are formed during winter. The Koi's age can be approximated by counting the light and dark bands as one year. This technique has recently (5/29/2000) been successfully used by Canadian fishery researchers in Halifax to determine that ocean perch reach the age of 75 years, instead of 30 years as was previously believed. How old is your favorite Koi? Q: Koi CPR Koi CPR? A: Koi CPR It's a beautiful morning and, as you take your first sip of coffee of the day, you venture outside to visit your pond. As you focus on your surroundings you realize that one of your Koi is missing! What the heck happened? Well, during the spawning season your male Koi will do almost anything to impress their would-be mates, including jumping. Sometimes the jumping gets a little out of hand and they jump right out of the pond! If you find your Koi lying beside the pond, there still may be some hope for his survival. Fishy CPR! Don't worry, you don't have to press your lips against theirs! According to an article that appeared in the Southern Arizona Koi Association newsletter, written by Del Pearce, fish CPR basically involves returning the fish to the pond, submerging the fish in the pond, and gently forcing oxygen-laden water through the their gills.This is done by forcing the gills to operate in as normal a manner as possible.There is a small spot at the lower portion of the head (his chin) where the gills come together, if manipulated gently they will cause an almost normal gill action. The problem with a large Koi is that holding them while manipulating their gills can cause severe bruising on their heads. Additionally, if you can keep the fish moving in a relatively normal manner, this helps also. As long as the fish is still moist, when you find him landlocked, you have a fighting chance of saving him from certain death. In the story told by Del Pearce, it took him an hour of constant work before the fish was revived to the point of swimming on his own.It doesn't always take this long, but it's worth the effort. This article was taken from the 2001 Summer Edition of Lifestyles Magazine (Watergardening) Q: Koi Taxonamy How are Koi (Cyprinus carpio) classified in the taxonomic hierarchy? A: Koi (Cyprinus carpio) are classified in the taxonomic hierarchy as follows: Kingdom - Animalia Phylum - Chordata SubPhylum - Vertebrata Superclass - Osteichthyes Class - Actinopterygii (Ray finned fishes) Subclass - Neopterygii Infraclass - Teleostei (Bony Fishes) Superorder - Ostariophysi (Carp, minnows, Catfish, etc - have Weberian Apparatus) Order - Cypriniformes (Carp, Minnows, etc.) Family - Cyprinidae Genus - Cyprinus Species- Cyprinus carpio Subspecies - (koi)* Note: Cyprinus spp. refers to all species in the "Cyprinus" Genus *Subspecies has not been assigned official Latin name yet. Q: Koi can hear Can Koi hear? A: Carp and Koi have some improvements to their hearing system that improve the range of sounds they can hear. Most fish cannot hear frequencies above 1,000 hertz, but Koi can hear 3 times higher, up to 3,000 hertz. The reason for this is Koi have a type of amplifying system called the Weberian Apparatus that other fish do not have. It consists of 4 pairs of bones called ossicles, which form a linkage connecting the inner ear to the swim bladder. This connection of the swim bladder's air chamber to the inner ear greatly improves the Koi's ability to hear. The Otolith is the Koi's "ear bone". Otoliths are part of Koi's inner ear or vestibular apparatus, and reside in the cranial cavity. They are composed of calcium carbonate and protein. They function as sound receptors and are also used for balance and orientation. There are 3 pairs of otoliths or ear stones in the inner ear of a Koi. The largest pair of Otoliths, the sagittae, are routinely used for aging. So Otolith is synonymous with sagitta. Humans have otoliths too, but our hearing system is much more advanced than Koi. Q: Koi Nutrification Koi Nutrification? A: Koi are sometimes described as ammonia machines. In other words, their respiration through their gills and waste products produce what shortly becomes toxic levels of ammonia. It has been demonstrated that after 2 to 7 days, the ammonia concentration starts to level off and then actually declines. This is attributed to a gram negative bacteria named Nitrosomonas europaea. Nitrosomonas converts ammonia to nitrite, and is generally credited with being the first half of a biological filter. Nitrite levels from the converted ammonia then rapidly build up to even more toxic levels. Another bacteria Nitrobacter winogradsky had been thought to be the converter of nitrite to nitrate. Recently, with the benefit of the most modern technology, including DNA sequencing and analyses, it has been demonstrated that the actual converter of nitrite to nitrate in aquaria is Nitrospira marina (Hovanec, T. A. and E. F. DeLong. 1996, "Comparative analysis of nitrifying bacteria associated with freshwater and marine aquaria", Appl Environ Microbiol 62:2888-2896 and Burrell, P. C., J. Keller and L.L. Blackall. 1998, "Microbiology of a Nitrite-Oxidizing Bioreactor", Applied Env Microbiol 64:1878-1883.). Generally it has been observed that the bacteria that convert the nitrite to nitrate don't show up until ammonia concentrations build up to high concentrations (see test results below). So the Nitrospira marina doesn't start to show up or become effective until after the ammonia levels start to spike. Then it takes 4 to 8 weeks to become effective enough to level off and reduce the nitrite concentrations. The Nitrospira marina is the second half of the biological filter, and takes much longer to mature than the first half.. The nitrates are then removed by algae and plants which completes the nitrification process in aquaria and ponds. They also can be removed by frequent water changes. Koi growth can be stunted by high levels of nitrates. Unfortunately, many Koi have been lost because of total ignorance or a poor understanding of this process. What is not well understood is you can completely destroy a great biological filter by rigorously cleaning it with chlorinated tap water, and throwing out the media and replacing it with new media. Some chemical treatments can also destroy it. High levels of nitrite lead to brown blood disease. Brown blood disease occurs in fish when water contains high nitrite concentrations. Nitrite enters the bloodstream through the gills and turns the blood to a chocolate-brown color. Hemoglobin, which transports oxygen in the blood, combines with nitrite to form methemoglobin, which is incapable of oxygen transport. Brown blood cannot carry sufficient amounts of oxygen, and affected fish can suffocate despite adequate oxygen concentration in the water. This accounts for the gasping behavior often observed in fish with brown blood disease, even when oxygen levels are relatively high. In humans high nitrite levels cause "blue baby disease". Sodium chloride (common salt; NaCl) is used to "treat" brown blood disease. Calcium chloride also can be used but is typically more expensive. The chloride portion of salt competes with nitrite for absorption through the gills. Maintaining at least a 10 to 1 ratio of chloride to nitrite in a pond effectively prevents nitrite from entering Koi. Where Koi have bacterial and/or parasite diseases, their sensitivity to nitrite may be greater, and a higher chloride to nitrite ratio may be needed to afford added protection from nitrite invasion into the bloodstream. As a general rule, strive to maintain at least to 50 to 100 ppm chloride in pond waters as "insurance" against high spikes of nitrite concentration. 1,000 ppm of salt is equal to a 0.1% level. Brown blood disease can be prevented, or at least minimized, by close monitoring of nitrite, chloride, and total ammonia nitrogen (TAN), and by maintaining the proper chloride to nitrite ratio. If brown blood disease does occur, the condition can be reversed by adding salt to the water. Koi surviving brown blood disease or nitrite stress are more susceptible to bacterial infections, anemia (white-lip or no-blood), and other stress-related diseases. These secondary problems, such as Aeromonas or Columnaris infections, often occur 1 to 3 weeks after brown blood disease occurs. Remember: 1 ppm of ammonia can lead to almost 3 ppm of nitrite because one Nitrogen atom in a molecule of ammonia (molecular weight of 17) forms one Nitrogen atom in a molecule of nitrite (molecular weight of 46), so 17 ppm of ammonia would lead to 46 ppm of nitrite. In other words, the ratio of the molecular weights (46/17) can potentially multiply the ammonia levels by 2.7 times. 1 ppm of nitrite can similarly lead to 1.35 ppm of nitrate (62/46). 1 ppm of ammonia can for the above reasons lead to 3.65 ppm of nitrate (62/17). Q: Koi Filtration What about Koi Filtration? A: State-of-the-Art in Pond Filtration By David A. Dec ©2002 Pond filtration requires two main components; both mechanical and biofiltration. First, the mechanical filtration needs to remove both the suspended particles and the debris that has settled to the bottom so the water is clear, and we can see our fish and plants. If not removed, this organic mulm can harbor dangerous organisms and chemicals that threaten the health of our pond. Second, the biofiltration needs to change the toxic chemicals like ammonia and nitrites, to harmless or helpful chemicals like nitrates, oxygen, and nitrogen. This is done with biologically active bacteria species through the Nitrification process. Effective Pond Volume A recent buzzword in pond circles is “Effective Pond Volume”. People have found that selecting a filter based on how many gallons their pond holds is not at all accurate. Since biofiltration is dependent on the ammonia load from the pond’s fish, biofilters needs to be sized according to the amount of fish wastes produced each day in the pond. This depends on the quantity of foods they consume each day. Selecting a swimming pool filter is done by matching flow rates. However, the proper way to select a filter for a pond is to determine the maximum number of fish you are planning for the pond, and the weight of food you will feed them daily, plus the amount of algae and other natural pond food they eat. Typically the amount of food Koi eat is 1% to 3% of their weight. How Much Food Then you select the filter that will process that weight of food per day. However, this is not an easy task because many filter manufacturers’ feel compelled to match their competitors' exaggerated claims of their filters' capacities, which means the ability to process food to ammonia and nitrite levels of 0.0 to 0.1 parts per million (ppm). Unfortunately these manufacturers’ grossly overstate the amount of fish wastes that their filters will handle. We have done our own research into this and found most of their claims to be outlandish. Surprisingly if they were more accurate they would probably sell larger or multiple filter units to their customers, the result would be healthier fish, and everyone would be happier. Don't forget the square area of the pond itself supplements the square area of the filter media, and can easily add 25% to 200% to the bacteria's total processing surface area. Overfeeding the total square area for nitrification causes the ammonia and nitrite levels to increase to dangerously toxic levels, without frequent water changes. That is why many ponds are running ammonia and nitrite levels of 0.5 to 1 or more ppm, and their owners are wondering why their fish are sick and dieing. Filters can also be combined in parallel or series depending on the application or the amount of food that needs to be processed. Surface Area Efficiency Our own research, as well as others’, has shown that filters process about 0.1 gram of food per day per square foot of surface area in the filter media, at maximum nitrification efficiency. In other words, they convert the toxic ammonia to nitrites, and then the toxic nitrites to nitrates via the nitrification cycle. Since the bacteria live on the surface of the pond walls and filtration media, a larger surface area in the filter means there is more room for a larger bacteria colony to do the biofiltration. The surface area in a filter is the filter media’s surface area per cubic foot, times the number of cubic feet of media. A larger total surface area allows larger colonies of nitrifying bacteria to adhere to it. The surface area in a filter is what makes it work. The larger the surface area the greater is its biological activity. The most important consideration in purchasing a filter system is its surface area efficiency in dollars per square feet. Sand The surface area per cubic foot depends on the media. For instance, very fine sand with a diameter of 0.125 mm or .005 inches has 8,000 square feet of surface area per cubic foot. So a sand filter with 2 cubic feet of very fine sand has 16,000 square feet of surface area so it can process 1,600 grams or 3.5 pounds of food per day. Sand of this diameter in a filter results in a total cost about a nickel per square foot of surface area. Sand with a diameter of 0.5 mm or .02 inches has 2,000 square feet of surface area per cubic foot; and results in a cost of about $0.20 per square foot of surface area. Plastic Bead Filters Plastic beads with a diameter of 5 mm or 0.2 inch have a surface area of 200 square feet per cubic feet or about 40 times less than sand. So a bead filter with the same 2 cubic feet of beads has only 400 square feet of surface area, so it can only process 40 grams or 1.5 ounces of food per day; much less than that for the sand filter. For this reason when beads are used in filters the typical cost is $1.00 to $2.00 per square foot of surface area or 5x more than sand. It is obvious that the media needs to have a very large surface area to host the nitrification bacteria. All the media up to this point have been solid, i.e. sand or plastic beads. Hollow Media A newer development is hollow media. If you took a miniature plastic “hollow drinking straw”, and formed internal walls inside it, you would not only have the external surface area, but also an internal surface area. They are 5 mm in diameter and vary in length from ¼” to ½”. This media has 750 square feet of surface area per cubic foot. So a filter with 2 cubic feet of media will have 1,500 square feet of surface area, and will be able to process 150 grams or 1/3 pound of food per day. This is over 4 times more efficient than bead filters, but 1/10th of the sand filter’s surface area. Its cost when used in a filter is about $0.75 per square foot of surface area or more than 3x sand. The first disadvantage of this new media is the difficulty of manufacturing it. The units are obviously very small and have a very complicated design, which makes them very expensive at about $200/ cu ft. The second disadvantage is they are made of styrene. You can test this by putting some media in water. If it sinks it is most likely styrene. Another test is to burn it since styrene burns with a black sooty smoke. Styrene oxide as a contaminant of styrene is known to be very toxic to bacteria, which would be a disaster to bacterial colonies for nitrification. Filter Operation It is true that sand filters have been used in almost every swimming pool in the USA. They have been proven and constantly improved after millions of installations. They are obviously very effective, inexpensive, and are very easy to clean. In fact, they are almost self-cleaning. You just turn a valve to backwash them. This saves lots of time, inconvenience, labor, mess, and wear and tear on the pond fish, and it automatically provides the small but frequent water changes needed to remove the dissolved chemicals. During normal operation the water flows in through the top valve, travels down through the sand or filter media where the debris is trapped, and flows into 6 to 8 perforated plastic laterals connected to a hollow stem, and then out through the top valve back to the pool. During backwash the water is re-directed down the stem and through the plastic laterals, flowing up through the sand, carrying the debris out through the top valve to waste. One way to select a swimming pool filter is by flow rates. For instance, if you are planning a flow rate of 110 GPM or 6,600 GPH you will want one 36" diameter filter, or possibly split the flow between two 24" filters, which would be cheaper. Filtration flow rates in gallons per hour vary with the size of the filters as follows: Filter Diameter Typical volume in cubic feet Flow Rates in GPM Flow Rates in GPH 12" 0.5 8 - 11 480 - 660 14" 0.75 12 - 18 720 - 1,080 16" 1.7 19 - 28 1,140 - 1,680 18" 2.6 29 - 34 1,740 - 2,040 20" 4 35 - 45 2,100 - 2,700 24" 5 46 - 68 2,760 - 4,080 30" 12 69 - 100 4,140 - 6,000 36" 22 101 - 165 6,060 - 9,900 42" 33 166 - 269 9,960 - 16,140 48" 47 270 - 360 16,200 - 21,600 Notice that two 36" filters have about the same performance as one 48" filter, and are a bit cheaper, but will have much less back pressure. Sand filters are typically charged with 1/2 of their cubic foot volume, with 100 pounds of sand being equivalent to 1 cubic foot. Vacuuming Another benefit of the "pressurized" sand filters is the ability to use the pump's suction line to operate a vacuum to clean the bottom of a pond. The vacuum hose typically plugs into a skimmer's suction line to the pump. The valve is turned to “Waste” so the vacuumed waste does not go through the filter, but goes directly to the waste line. This same vacuum hose can also operate a mechanical robot vacuum that automatically vacuums the pool's bottom. These robots are made for either concrete or EPDM liners. Skimmers With the pressure type filter the skimmer’s strainer-basket becomes the pre-filter. We often have to clean the skimmer strainer-basket of algae, leaves, and debris twice a day, and the pump strainer-basket at least twice a week. However, it is quite easy, you just remove the basket, hose it off, and replace it. It only takes a minute or two. You can use chlorinated garden-hose water since the basket is not part of the biofilter. Problems with Sand There are 2 main objections to sand filters for ponds. First and most important, they can plug up if: Loaded at 100% of the manufacturers’ recommendation for sand, which is about 1/2 full. Not backwashed at least once per week. Not backwashed with a powerful enough pump. Second, some opponents say the water travels through it too fast to allow for effective biofiltration. They say the residence time is too short. However, they ignore the fact that the water makes many more trips through the media for a given time period, so the actual contact time per hour is about the same. Large City Aquariums use Sand Filter Most if not all large city Aquariums use sand filters. They know how to properly use them, and have found the efficiencies to be unsurpassed. Pea Gravel Not knowing how to properly use a sand filter some people tried replacing the sand with pea-gravel, which has a surface area of only 100 square feet per cubic foot, or 80 times less than sand. Needless to say pea-gravel is not the answer. Sand Diameter mm Area in square feet per cubic foot (ft2 / ft3) Pea Gravel 10 96 Very coarse 2 479 Coarse 1 958 Medium 0.5 1,917 Fine 0.25 3,833 Very fine 0.125 7,666 Very very fine 0.0625 15,333 Bead Filters Somebody noticed that the plastic-bead feedstock used by plastic injection molders had diameters much smaller than pea-gravel, but larger than sand. These solid plastic beads, at 3 to 5 mm, 1/8” to 1/5", have a surface area per cubic foot of 200 to 300 sq ft / cu ft, which is better than pea-gravel, but 30 to 40 times less efficient than sand. In other words, you might need 30 to 40 bead filters to match the biological efficiency of a single sand filter. Plastic beads diameter in mm area in square feet per cubic foot (ft2 / ft3) 5 192 4 240 3 319 2.5 383 2 479 1.5 639 1 958 In order to get more surface area in the bead filters manufacturers simply try to put more beads into the filter; since the beads have much less surface area per cubic foot. They jam it almost full; in some cases they fill 90% of the filters' volume with beads. This leaves little room for backwash turbulence to develop. So even with the dramatically reduced efficiency the literature shows many bead filters are still plugging up: partly because of the overfilling, and partly for the same reasons listed above for sand filters; not backwashing often enough, and not backwashing with a powerful enough pump. So some manufacturers have added air blowers to try to reduce this plugging tendency. Unfortunately, when the beads clump up forming channels the air simply goes through the path of least resistance, the channels, which means it has no effect. The manufacturing of “bead” filters was very simple and became quite popular. It consisted of buying standard sand filters at wholesale, dumping the sand, and inserting the polypropylene or polyethylene plastic beads, and jacking up the price 3-4X for sale to the pond industry. The drainage plugs were now referred to as “sludge removal ports”. Then some very clever bead filter manufacturers, realizing they needed to add more value, added small UV lights, and compressed air-lines. Bead Media Washout During the backwash operation sand being heavier than water falls to the bottom of the tank, instead of flowing out through the valve to waste. However, the plastic beads being lighter than water float to the top, and since they are smaller than the valve-strainer's holes, they are washed out through the valve into the waste stream; so more and more beads are lost during each backwash operation. This limits the size of the beads being used; the smaller the beads, the greater the surface area for bacteria, but the more bead loss during backwash operations. The larger the beads the smaller the surface area for bacteria, but the backwash bead loss is reduced. So the bead filters are limited in efficiency. Pond Sand Filter Research Our research focused on under-loading the sand filters, and backwashing them more frequently with higher pressures and flow rates, in order to take advantage of the greater food processing surface areas, while eliminating the chance of plugging. The other advantage of the sand filters is they are more reasonably priced. We discovered a sand loading that results in a high efficiency yet doesn't plug. Other sand filter media investigated included coarser sand, porous ceramic material, and crushed lava rock. Other hollow media were also looked at. While it is true that pressure type filters such as sand filters may require a little more electricity to operate, most pond owners are willing to spend a little electricity to replace their labor. Owners of these filters want something that will do the job better, and with less labor. In the USA, too often our “Honey-Do Lists” are too long to allow using more labor-intensive filters. Settling Tank Filters are Labor-Intensive However, in Japan and China where labor can be cheaper than electricity, the standard for Koi pond filtration has been sedimentation-type tanks in series. They have usually consisted of three to four rectangular or cone-shaped tanks, with outlet valves on the bottom of the cones, and with the tanks plumbed in series. Peter Waddington in his book "Koi Kichi" describes these systems and some improvements in detail. The combined volume of the tanks depends on the pond size, and ranges from 6 to 30% of the ponds volume: Pond size Flow rate GPH % of Pond 1,450 500 6% 3,000 1,000 8% 4,500 1,300 10% 8,000 2,000 14% 15,000 3,000 20% The first tank, sometimes referred to as a pre-filter, has its intake coming in tangentially causing the water to swirl in a circular or vortex motion. Large particles of algae and gunk settle down into the bottom of the cone and are drained to waste when the bottom valve is opened. The second tank has hundreds of bottlebrushes hanging into the water. They provide some further mechanical filtration. The third and fourth tanks have layers of a stiff fiberglass like matting material, which do the biofiltration by providing the surface area for the bacteria to live on. Proponents of this system point out the long residence time of the water in contract with the matting materials, which they say allows for better biofiltration. Second they point to the electrical power savings available with these systems. This system works, but it has 4 drawbacks. First, it is very labor intensive especially when it comes to cleaning out the brushes and matting material. In fact, it is almost a full time, messy and smelly job to maintain. The bacteria in a good biofilter looks like black muck and smells like sewerage. Second, it is not too good for mechanical filtration, especially for very small particles. Third, it turns out to be a paradise for worms. Fourth, it is very expensive with prices of $5,000 being typical. There is a new centrifuge type mechanical filter that adds even more cost to these filters, but does improve the mechanical filtration. It adds another $2,000 to the total cost. Cheap Imitations There are some cheap imitations of this system that use only 1 tank, not the typical 3 or 4, and the 1 tank is also much smaller than 6 to 30% of the pond's size. In fact, for a 5,000 to 10,000 gallon pond, it is not 500 or 3,000 gallons, but the single tank is about 25 to 50 gallons, which is obviously way too small for effective filtration, either mechanical or biological. It is still a messy and smelly job to clean, and it must be cleaned more often than the larger tanks, even though some manufacturers claim they "only have to be cleaned once a year". Some companies charge $500 just to clean them. These cheap imitations of the Japanese settling tank filters are surprisingly expensive at $1,000 to $3,000, and simply do not do the proper mechanical and/or biofiltration job for a fishpond. One of the major problems of cleaning the settling tank type of filters is often they are cleaned using chlorinated garden-hose water, which kills much if not all of the biologically active bacteria. This can mean a whole new "ageing or maturing cycle" taking from several weeks to a couple of months before the filter is 100% effective again. This can cause harm to the pond fish suffering through this adjustment with high levels of ammonia and nitrites, which can kill them. State-of-the-Art Filters For all of the above reasons the latest generations of sand filters currently represent the “State-of-the-Art” in pond filtration, and they are surprisingly inexpensive, especially compared to the labor-intensive sedimentation tank systems. They have all the benefits of more expensive filtration systems, without the plugging problems, and they are 10 to 20 times more efficient than bead filters. The most important measure of a filter's efficiency is its cost in dollars per square feet of surface area. In other words, how much does the biological activity you need cost? Q: Koi Shows What about Koi shows? A: Head Koi Judge Grant Patton and assistants Penny Patton from South Carolina, and Roger Phillips from California, judging Koi entrants in a "show bowl". They often give the exhibitors their opinions about the Koi's stronger and weaker features, and usually do so in a very supportive manner. However, when a Koi has been misclassified they will also point that out, and not consider the Koi for judging. Some Koi can be entered in several different classes, i.e., Kohaku or Tancho, Bekko or Ginrin Bekko, etc. Picking the best class, i.e., the one with the least competition is something seasoned exhibitors consider. Some will even move their Koi up a size to a class with easier competition. Usually each Koi variety is judged separately in each of the different size groups (sometimes as many as 16 different sizes), and then the overall variety winner is judged. After that the Show's Grand Champion and Reserve Grand Champion are picked, and then any special awards are made. Many shows now follow the English model where Koi are kept separate in their own clean 300 gallon tanks, isolated from all the other Koi and Koi tanks in the show. Even the judging bowls the fish are put into for the judges convenience are rinsed with bleach, kept separate, and assigned to and kept in each Koi tank. Nets, air stones and thermometers are scrupulously kept separate and not shared with other Koi tanks. Therefore the chances of diseases being transmitted from one exhibitor's tank to another are greatly reduced, but not totally eliminated. You still have visitors, especially children, putting their hands into one Koi tank and then into another, and sometimes even into their mouths. Even water testing is sometimes potentially contaminating when the same test vials are used in one tank, and then in the next, and so on. Overall Koi shows are a lot of fun and a good learning experience for all. |