Hello all,
I've been asked "What is SSA - and why is it so important?"
Specific Surface Area, or SSA for short, is the available surface area of any type of filtration media per square foot that nitrifying bacteria can live on. A biological filter, no matter what type or brand, is designed to house media that nitrifying bacteria live on in a bioflim for the purpose of metabolizing ammonia and waste from pond water. 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. There are other strains of heterotrophic bacteria and enzymes that participate on the over all nitrification cycle as well. The bacteria live on the surfaces of what ever type of media is inside the biofilter in what is called the "biofilm layer". The higher the SSA, the more bacteria that can live within the filter, thus the higher the SSA, the more ammonia and waste that can be metabolized. SSA is the base figure used to calculate how much fish waste and ammonia that a biological filter can metabolize in a 24 hour period. SSA is the common denominator across all biological filters and media. It is the "Horsepower & Gas Mileage" rolled into one easy to understand number. "All biomedia in fish pond filters or bio filters of any type can be classified according to its specific surface area (SSA). The higher the SSA the more probable is it that the biomedia will be more effective in a fish pond filter. SSA refers to how much surface area per unit volume of a type of media is available for colonization by bacteria inside fish pond filters." Excerpt from www.clean-garden-ponds.com/biomedia.htm
Virtually all media manufacturers publish the SSA of their biofilter media. For example, Matala publishes the SSA of each of their filter pads on their web site. Their pads SSA's range from 10.33 to 28.5. Polyflow publishes on their web site the SSA of their filters pads ranging from 31 to 49. Bioballs range from 16 to 21 SSA, lava rock averages 14.35 SSA, Springflow strapping type media ranges from 10 to 15 SSA, pot-scrubbers range from 55 to 80 SSA, HydroFiltersilk has a 61 SSA, plastic and foam beads range in SSA from 60 to 80 SSA, Kaldness has a 41 SSA, and bio-tube media has 125 SSA. There are many other types of media also that I haven't listed here as well. 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.
All biological filters contain media. All media has measurable surface area.
It is impossible to know how many fish a biological filter can support, and how much fish waste and ammonia the biological filter can metabolize without knowing its SSA. SSA tells you how much nitrifying bacteria can live on the media - the biofilm layer as it is commonly refered. You don't know how much gasoline your car burns without knowing the Miles Per Gallon (MPG) - well, SSA is the same type of critical number to know.
It is commonly known, and widely published in study after study that it takes an average of 10 square feet of biofilm (SSA) to metabolize 1 gram of phyiscal fish waste per 24 hours. It takes and average of 50 square feet of biofilm (SSA) to metabolize 1 gram of ammonia per 24 hours. Fish, including koi, produce an average of 33% of their total body weight in waste per 24 hours. Fish, including koi, excrete .1 grams of ammonia per 1,000 grams of body weight per 24 hours. These statistics are compiled from State Fisheries, University Aquaculter Studies, Hatcheries, Breaders, and Human Food Fish Farmers.
SSA tells you exactly how much biofilm a biofilter contains. The SSA then tells you how much ammonia and waste it can metabolize in a 24 hour period. Once you know the maximum amount of ammonia and waste the biofilter can metabolize, you can calculate how much fish, by weight, produced the waste and ammonia.
For example: A biofilter with a Total SSA of 2,000 can metabolize 200 grams of fish waste per day. (2000 SSA x .1 = 200) That 200 grams of fish waste was created by 600 grams of total fish weight. The 2000 SSA tells us that it can metabolize 40 grams of ammonia per day. (2000 SSA / 50 = 40). The weight of the fish, 600 grams, tells you that you can feed the fish 21 grams of fish food per day. (Fish, including koi, consumer and average of 35% of their total body weight per day, thus 600 grams of fish weight x .035 = 21)
So to sum up. SSA (Specific Surface Area) is the total amount of space for biofilm colonization within a biofilter. The SSA number tells you exactly how much ammonia and waste in can metabolize per day. The total waste tells you have much fish, by weight, made it. The total weight of the fish tells you how much food to feed the fish per day. Without knowing the SSA of your biofilter - you can only guess as to fish loading and feeding.
SSA tells you how much fish your biofilter can effectively support.
Thanks so much for the question.
Sincerely,
John Russell
President/CEO Russell Watergardens