DevotedToDiscus
Fish Herder
I run Eheim Peat in my filters for my Discus tanks,and it is a better way to lower and control pH than adding Acidifier. However, it depends what your current pH is. If it is less than 7.5 don't mess with it, unless you are trying to breed them, as they will be just fine in water up to 7.5
Clean stable water is the your number one priority. Producing RO water in the quantities required for a general Discus show aquarium, with regular large water changes, is not viable in my opinion. Reserve your RO water production for breeding and growing young fish.
Note: Sorry, just read your reply about your water being pH 8.4.......... My suggestion would be Peat, and Co2 to control it by 1 degree.
Clean stable water is the your number one priority. Producing RO water in the quantities required for a general Discus show aquarium, with regular large water changes, is not viable in my opinion. Reserve your RO water production for breeding and growing young fish.

Note: Sorry, just read your reply about your water being pH 8.4.......... My suggestion would be Peat, and Co2 to control it by 1 degree.