Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I think there may be 2 things going on.
1) Debris in the water
2) Tannins staining the water.
Here is how I would handle this:
Very large water change, as close to 100% as possible.
Dig down into a corner of the substrate and get the siphon down to the bottom of the tank, while holding the substrate back so you do not lose too much through the siphon.
Refill only partially while siphoning. Do the refill over the rest of the substrate so the water washes through the substrate and out the siphon. Keep on doing this until the water is a lot clearer.
Put a plate or plastic bag over the substrate and pour the water in slowly, allowing it to seep over the edge of the plate.
I would get a filter that is easier to clean, such as the Aquaclear, and stuff it full of fairly fine media. It comes with a coarse sponge, and that is OK. On top of that add finer media, ending with polyester floss. You may have to rinse this media daily if the crud keeps coming up. The activated carbon will help remove the tannins, but it is active for only a few days. Large water changes are really the best way to get rid of the tannins. Keep this filter on the front of the tank and deal with the crud as often as you can. As long as the crud stays in the system (and the filter is still part of the system!) it can still stain the water with tannins. The more often you can clean the filter the faster you will get rid of it.