So I do use canisters with my discus. However, most breeders I know don't. Moving forward I won't either.
I like canisters, especially the new advanced fluvals. The g6 continues to be my favorite overall filter. It is just plain user friendly. Albeit, very expensive.
The fx5 is an absolute monster, and is my second favorite filter.
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However, with discus... Most of this makes absolutely no difference. Think about it; 1-2 DWC. Infact other then medicine removal; Chemical filtration is useless. Additionally; my mechanical are never dirty... DWC is your mechanical.
So the only true useful filter for discus is bio... And with the amount of poo and food for discus, bio is very important to keep the tanks from having ammonia spikes.
So you might just consider 3-4 breeder (sponge) filters & a good air pump. Breeders also add air to the water, which is needed in high temp tanks.