What 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 bio filter media. It is measured per square foot, and it is what bacteria can live on. A biological filter is designed to house media that nitrifying bacteria live on to metabolize organics and fish waste from water. The bacteria live on the surfaces of the 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 that a biological filter can metabolize in a 24 hour period.
It 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.
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.
