Very true. Worry more about your bio filtration and less about your mech and chemical filtration. for your 55g get a emporer 400 run it with out cartriges. this will keep the water flow very high. keep your tank very basic so when doing your 2 40-50% water changes per week you can vacuum up all the debree. With this set up you can have the 6 adult discus you would like even though this is over population. Also best if you can raise these from 2-3" juvenilles. I've had adults that when put in a crowded situation get stressed and quit eating even in pristine water conditions.hillbilly;588872; said:Canister filters are not necessary with discus because they need clean water all the time. Filtration is less important because the tank should always be clean. This is best done with water changes, instead of filtration. Some breeders only use sponge filters and change 100% of the water daily. I don't go to this extreme, but I make sure the water is always clean by stocking lightly, and changing water every other day. These fish evolved in acidic conditions where microbial populations are low, thus are more susceptible to "dirtier" conditions than most other fish. They are really easy to keep, as long as you keep up on your water changes, instead of relying on filtration.
My set up is a 85 gallon with a wet/dry rated for 150/200 gallon tank I run and 900 gph return. I changed 40 gallons every 3 to 4 days. Stocked with 8 discus 4-5" 15-20 cardinal tertas, 2 clown loaches. I also have alot of plants which increases the maintence workload but my fish are happy and healthy.