[Sk8r]

I wholly agree with that, DesertRat. Tap can cause you soooo much trouble. It's also not true that it doesn't matter if you set up your tank with tap, because it's just---I dunno, exempt from logic or something. NO! Use ro/di.

There's this thing called TDS. You can get a meter for it. It measures Total Dissolved Solids. It measures how much is dissolved in your water...they say, for instance, that Colorado River water is 'too thin to plow and too thick to drink' when running in the Grand Canyon. That's a real high TDS, got it? So ro/di is zero! If you have, say 3 to 5 in fresh water---that's not good. Some of what's dissolved can be copper [lethal] or stuff from nearby farm runoff---, heck, just use ro/di. Once you add ocean salt mix, your ro/di quickly becomes non-zero again---but in a GOOD way, got it? You want the good stuff dissolved in your ro/di, AFTER you add the salt mix. You want it to BE ocean water. Does that make sense?