The best success i have had at discus is with straight tap water, mine breed like rabbits, Ph 7.3, temp 28 Never 30-32 unluss you have a case of white spot or need to medicate, Kh 3, NH4 0, NO2 0, NO3 0
Soon i will be using DI tap water with a secret recipe of additives, please note you cannot use Just DI water it is too pure and will dissrupt osmo regulation
http://photobucket.com/albums/v305/dogmatixnz/Discus/