i agree with discus owner and nitrates, thats why isaid 30%~50%Ullopincrate;2887358; said:We could all speculate, but we know water changes are good. Check the parameters of your tank ammonia,nitrite,nitrate, ph. Adjust water changes as necessary. But I would do a minimum of 20%. I'm not sure I agree with 50% but we all have opinions. Talk to Discus owners. There are some who do daily changes.