Sponge Filters - Tech Talk 29
Air-powered sponge filters operate on the airlift principle to induce flow, so the taller the chimney, or lift pipe, the greater the vacuum and the flow of water.
Sponge filters do an excellent job of capturing solids. Unfortunately, a lot of these collected solids drain out of the sponge when it is lifted out of the water for cleaning.
An easy way to avoid this is to use a sponge-sized plastic bag or bucket. Gently place the sponge in it while under water, then remove the entire package. Squeeze out the fouling material, but do not clean too thoroughly because that will eliminate all the good bacteria that provide biofiltration.