PS I'd like an explanation from 'someone' - as to why a tank (with fish only) can't be set up with tap water - there are no major toxins that will harm fish - that are in tap water (that cant be neutralized) - the only problem is tapping off the water with tap water for evaporation MIGHT cause problems. If he/she is doing water changes - even that SHOULD not be a problem. But the best would be to use RO/DI, distilled water for new top offs (clearly).
Tap with prime should be fine for a fowlr with dimmer lighting. It is also used in some reefs successfully just fine...just depends on the source at that point.