Is RO water absolutelty necessary for Discus?
I would think your current tap water is just fine for discus. If you intend on breeding them then targeting a particular low PH is important, otherwise they do well in neutral waters too. There’s also little use in trying to make your water similar to your supplier, theirs can change without notice and differences can exists even between the various systems in the same store. You’d be best to keep a good steady chemistry and acclimate new fish very slowly to assure the least amount of stress possible when introducing them to the tank.
PS. I assume you are not adding ammonia to the tank for fishless cycling right? Not with live plants… Just making sure 
Hope that helps Giancarlo Podio, LMD
Category: Philippines Internet Koi Society
