I used to just buy the distilled water in the gallon jugs - but it's so dry here I'm running through water quite fast. So I recently started buying the water in bulk from the dispenser at the local wally-world. It's cheaper, and easier, plus I don't create all the plastic waste. It has several filter steps, one of which is reverse-osmosis, so I thought it would be ok.
However, I've noticed recently that a spilled drop of small amount of this water will leave a residue behind when it evaporates. Just like hard water does. So has anyone had any problems with this kind of water? Any suggestions on how I can test this stuff, ie do the aquarium water tests work ok to test hardness - and if so what is a safe level of hardness for cps?
In the past I never worried about these issues due to using pure distilled water - so this stuff is new to me. If I have to, I'll go back to buying the gallon jugs, but wow what a pain it's becoming!