I have an AquaClear 20 filter in my 5 gal tank that is almost cycled. This is a 3 stage filter, and I've recently read a number of suggestions to replace the carbon element with something more helpful or beneficial. This tank will only be for one Betta, some plants, and maybe some shrimp if I get more daring.
Any advice on a substitute/replacement for a carbon element?
This is late, but the best you could try is to dump the carbon out of the pouch thing and replace it. The beneficial bacteria live in the filter pouch and walls. Carbon will loose its "power" after a while.