What are the pros/cons/ramifications of using distilled water to start an aquarium and for water changes?
< This all depends on what you want to do. Generally distilled water is pure H2O and has no minerals or salts. Bacteria need some minerals like calcium for nitrification. There is no buffering capacity to the water. As the fish waste builds up, the water could quickly turn acidic and kill off all your fish. You need to add something to the water to maintain a stable pH. Their are many buffers sold in the aquarium trade by manufacturers that will put your ph anywhere you want it. Very good if you want to maintain soft water fish like discus, dwarf cichlids, cardinals etc... If you were keeping hard water fish then you would have to add lots of minerals to stabilize the ph at a much higher range, but this is easy to do. If you wanted to keep marine fish and reef invertebrates then the advantage of using pure water is you can add all the minerals you need in the exact amounts you need without worrying about existing minerals in tap water that may throw some equilibrium off. Many salt mixe
