Hey, ive read certain things about how the carbon media on a powerfilter may not be working. How can you tell if the water is going through your powerfilter in the apropriate manner?
That's a good questions, but I would say if you see the sponge changing colors on both sides, then it must be filtering through. Anyhow, these bags are made so that water passes through them, so I wouldn't worry about it too much unless you made your own type of sponge.