i went to some petstore yesterday and i saw so many saltwater fishes,corals,and inverts it was so cool. (MUCH BETTER AND HEALTHIER THAN ANY OTHER BIG PETSTORES). HE TOLD ME IF YOU WANT HEALTY FISH TOP OF YOUR EVAPROATED WATER WITH SPRING WATER. IS THIS TRUE?

I think RO water is best I think.. unless minerals evaporate too?
Probably cheaper as well.

spring water is way cheaper than ro water

If you've already paid for an RO filter, then I wouldn't bother paying any more for spring water, RO is equal in value to spring when it comes to topping up... RO is doing just what you need to the water.

(minerals don't evaporate)

I'd go with RO then. As you don't want to be constantly putting more and more minerals in without any coming out.

Any bottled water is fine and is essentially what RO is. Always be sure to buffer your water though because the pH of RO is usually close to neutral.

Sorry...but not all bottled water is created equal... There are vast differences...bottled distilled water can have traces of heavy metals, some spring water can have nitrates, along with other issues....I would say that if you have put a bunch of money into a reef system you want the water going in to be free of copper, lead, silver...etc...

RO water is pressure forced through a membrane that takes out almost all nasties that will cause a reef tank problems...if you want even better quality water then a RO/DI filter would finish off the perfect filtered water for a reef tank....

Also not all ro water has a low ph...I run my water through a ro/di filter and it comes out 8.05 on the PH scale....