- Aug 3, 2020
- Reaction score
I've been asked this question many times and I'm not sure I've ever given it the consideration it's due. I guess I haven't thought about it much. After setting up a sponge filter, I just assumed it was working. With all the bubbles coming out the top, through the tube, I have always known that there was a lot of water movement and pull through the sponge. I'd like to get some other opinion though. So the question is, how do you know if your sponge filter is working?