r/o versus distilled water

distilled water is purer than r/o.

Distilled water is okay for tanks, but RO/DI is better. I'd test any distilled water for copper before using it.

And...welcome to Aquaria Central 105man!

Good morning 105man!

Both right. Kind of. Depends on where you get them. Can't get more pure than glass distilled water, but that's the key issue. I have no idea how they distill the stuff in stores, and copper may be a problem. Distilled means that it's been turned to steam and recondensed, leaving the bad stuff behind, by the way.

RO actually means really, really finely filtered. It's passed through a membrane with little tiny holes that stop just about everything that's not water. Normally pre-filtered to get sediment and carbon filtered as well. Some ions get through, so some purists use a RO-DI (de-ionization) system to make it even purer.

Assuming it's a good unit, RO water does not need to be treated. Add salt, stir for hours to days to equilibrate O2 and C02 and add to tank.

I prefer RO water myself, though store bought distilled water works just fine, IME.

I would avoid the store bought distillwed water because most of the time, commercial distillaries are not going to use glass (expensive).. They'll use copper, and over time the copper will begin leeching into the water. Once that copper gets into your tank, it doesn't come back out.

When I first started keeping salties, I bought my water at the store. This quickly became both annoying and expensive. You can pick up a Kent 24gpd RO unit for around $100 if you look in the classified section of most fish boards. Ebay is also a good source for inexpensive RO units.

Oh and I use pure, untreated RO water for straight top offs. No Amquel, Prime or any of that other junk goes in my tank. Now ya know =)