It depends on which tank to be honest. Some of my tanks have more delicate species than the others.
I'll either use straight from the tap with some Prime, and we set up some 55g food safe barrels in the basement with heaters and circulating pumps. We have a water pump set up to pump from the barrels into those delicate tanks. The barrels allow the pH to lower to a safe level and "age" the water by time it's used. We have them hooked to refill using swamp cooler floats. We just add some Prime and let them do their thing.