[bekko]

John, you should fake an injury and try to sit on the bench as much as possible because you are playing out of your league.

Quote: All media has measurable surface area, and SSA commonly refers to how much total surface area the media has per square foot of that media.

The web site you referred to measures SAS in square meters of surface area per liter of volume. That's how the Europeans do it. In the US, engineers use square feet of surface area per cubic foot of volume when comparing filter media. It has been done that way for at least sixty years. Measuring surface area per square foot of media makes no sense since the media is three-dimensional. Matala can get away with it because they have a standard mat thickness. But, how deep is a square foot of Kaldnes? I don't know where your numbers came from, but they are very non-traditional. The least you can do is provide units of measure.

Quote: The two primary forms of bacteria that make up the nitrification cycle within biofilters is Nitrosonomas and Nitrobacter. As most of your already know, Nitrosonomas bacteria convert ammonia to nitrite, and the Nitrobacter strains of bacteria convert that nitrite to nitrate.

Well, actually they are finding that you can not attribute nitrification to these two species alone. Nitrosomonas (not Nitrosonomas BTW) is often not even a dominant ammonia autotrope in many systems. The current terminology is to just call them nitrifying bacteria and leave it at that.

Quote: It takes and average of 50 square feet of biofilm (SSA) to metabolize 1 gram of ammonia per 24 hours.

That is a good number to use for design purpses. However, the reported range in the aquaculture literature is 0.1 to 3.0 grams of total ammonia nitrogen (TAN) removed per square meter of biofilm per day. That equates to 4 to 110 square feet of biofilm per gram of TAN removal per day. Removal rate is a convenient way to approach the issue, but the background level of TAN is also an important consideration. At higher background TAN concentrations the removal rate is higher, but the background concentration may be unacceptable from the standpoint of fish health.

Quote: Fish, including koi, produce an average of 33% of their total body weight in waste per 24 hours.

Where did you get that number? Assuming that the fish is not growing and all of the feed is converted to waste the feed rate would have to equal 33% of the fish body weight per day on a wet-weight:wet-weight basis. Thus, the weight of dry pellets fed daily would equal about 10% of the fish's body weight. A fry can eat that much, but by the time a koi is large enough to sell it will not eat more than about 2% of its body weight per day.

In designing a filtration system, it is customary to work from the maximum amount of feed to be added each day - not the number or weight of the fish. For a biofilter, nitrogenous waste is the primary concern. The dominant source of nitrogen is protein in the fish feed. The feed bag will tell you the protein content - typically 32 to 40%. Protein contains 6.25% nitrogen. Ammonium (NH4) is 82% nitrogen. Therefore, each gram of 36% protein feed will be converted to 0.03 grams of ammonium (36% x 6.25% / 82%).

Quote: These statistics are compiled from State Fisheries, University Aquaculter Studies, Hatcheries, Breaders, and Human Food Fish Farmers

Mrs. Paul and McDonalds are my favorite fish breaders and I've been immersed is aquaculture R&D for a very long time. If you're serious about this stuff then you should do more homework. Do literature searches for publications by Tim Pfeiffer, Mike Timmons, Tom Losordo, Bjorn Rusten, John Colt, Ron Malone, Ep Eding, Phil Lee and Shulin Chen. Shulin Chen has focused on foam fractionators but is well versed in all aspects of aquaculture water treatment. I mention Dr. Chen specifically because he is right there at Washington State University, Pullman Campus. Give him my regards.

-steve hopkins