i just noticed one of my double sponges is not letting air bubbles out anymore and i tried cleaning in and then it was fro a bit letting it out when i tilted it on its side then it stopped again... i hav two others taht are really slow to let air bubbles ou... is it an issue of air power? dirty sponges? defective something or do i just suck at it?
It could be your pump, but the sponge filter itself is most likely the problem. Take your airline off and submerse it to see how strong a stream of bubbles you get is. If you get a nice healthy flow of air, it's going to be the filter itself.
I've noticed on some of mine that they have somewhat of a diffuser built into them so that you don't need to try and add an airstone to get smaller bubbles. These small holes are prone to clogging from algae and bacterial build-up. Take the sponges off and soak the plastic parts only in either a bleach or peroxide bath for about 10 minutes. After that rinse it very well and reassemble and place back in the tank. Works like a charm for me.