So I noticed some leftover flakes had fallen on the back end of my sponge filters in my 20g today, pulled them out, scrubbed them down, put them back in. When I did the wider tube on the top (where the bubbles come out) started filling with really icky, murky water, and I can't seem to get it to go away. I pulled them out again, replaced the tubing from the air pump to the gang valve (it was weirdly brown where I had it hooked up to the pump) and then from the valve to the filter. And I changed the valve again. The sponges don't look dirty, and I pulled the entire filter apart... I'm not sure what's going on, or how I can stop this weirdness.
Does anyone know what I should do? Take the filters out for a night and let them air dry or something?