Google isn’t helping. I want to know if a sponge over my air stone will be useful for increasing beneficial bacteria. The picture is what I did, also I saturated the sponge with QuickStart before submerging it. Is this pointless or will it help filter my tank and increase bb?
If you just stuck an air stone in a sponge I don't think it's going to work very well. A sponge filter uses air bubbles rising in a tube to create a flow of water into the sponge and up the tube. Without the tube you're not going to get the flow, and that's the important part.
If you put the air stone in a piece of rigid tubing, leaving room around the air stone for water to pass, and shove that whole assembly down into the sponge, then you've got a sponge filter.
I agree. You’ve got to have a casing (tube) around the air stone to direct the air bubbles upward drawing water into the sponge. Without the tube many of the bubbles are pushing outward into the sponge preventing tank water from getting sucked in.