Specific Surface AreaWhat is
Specific Surface Area (SSA),
and why is it so important?

Specific Surface Area, or SSA for short, is the total available surface area of all surfaces in a pond and any type of filtration media per square foot that bacteria can live on.  A biological filter, no matter what type or brand, is designed to house media that nitrifying bacteria live on to metabolize organics and fish waste from pond water.  The bacteria live on the surfaces of what ever type of media is inside the filter.  The higher the SSA, the more bacteria that can live within the filter.  SSA is the base figure used to calculate how much fish waste and other pond pollutants a biological filter can metabolize in a 24 hour period.  SSA is the common denominator across all biological filters and media. 

Specific Surface Area SSAIt is impossible to know how many fish a biological filter can support, and how much fish waste the biological filter can metabolize without knowing its SSA.  Manufacturers that don't tell you what their filter's SSA is, are doing a disservice to you, the pond owner.  Many manufacturers rely solely on mass marketing and pretty packaging to sell their products to you - and many intentionally leave out the critical information that you need to know about what their filter will, and will not do. 

When purchasing a biological filter separately, or in a pond kit, or having a contractor install one for you - it is critical that you know the Total SSA of the filter.  After all, if you don't know the SSA of the filter, how will you know how many fish that filter can support in your pond?



If the seller of the filter can't - or won't answer that most simple and basic question, then for the health of your pond and fish - find someone that can!

SSA is calculated per square foot.  For example, a piece of paper 1' x 1' with virtually no thickness, has 2 square feet of surface space. (1 square foot per side of the paper).  The SSA of a 1' x 1' piece of paper is 2.  A slab of stone 1' x 1' x 2" thick has a higher SSA than the piece of paper because the surface area of the  sides of the slab get added to the equation.  The slab has four 1' sides that are 2", or .17' thick.  Four sides 1 foot long multiplied by .17' thick = .68 square feet.  The total SSA of a cut stone slab is 2.68.

Top of Page