I don't want to use a R.O. unit

[forrest gump]

I don't have any corals, all I want are inverts and fish. Do I have to use R.O. water or can I use tap water? I was thinking about setting up a 20-25 gallon plastic container with fresh water. I would use a power filter with that poly-filter material and carbon to remove water impurities. I could then use this water to replace evaporation and for water changes. How does this sound? Does anyone have any experience with that poly-filter material? I read the reviews on it and it sounds like its suppose to be the best thing since sliced bread. I'm wondering if it's really as good as it says so I'm looking for anyone with personal experience with it. Thanks for your time.

 

[bdhough]

hmmm YES YES AND YES it is good.
Ro water has NOTHING in it. So you can properly buffer it and not worry about getting impurities in your tank. What size tank were you looking at? My two smaller tanks don't require much and 15 gallons can last me close to 2 months. While using tap is very easy, and you could use it with corals, its very conducive to algae growths. There are things in the water that chems and filters can't remove and will usually result in rampant hair algae. Your idea is sound but could be just as expensive in the short term. In the long term its hard to tell. If your method results in algae growths and a "ugly" tank then I say it wasn't worth it. If it works then you saved a little money.
I personally wouldn't even bother as you never know whats in tap. You are going to have to buy proper buffers anyways so i say just use RO.
One more thing. Make sure you buy a diverse cleanup crew. Many neglect this and in 2 months time youre fighting an uphill battle because you didn't buy any once the tank cycled.