Those who use tap water PLEASE READ!

[Imbarrie]

It is so clean and devoid of chemicals that it will diffuse chemicals from you.

 

[peteyboyny]

Safe drinking water is anything below 400 ppm. If its coming out of your tap at 81 ppm, that's not too bad. Out here in Rocky Point, NY I'm getting 74 ppm. As far as drinking RO water, it's fine. Drinking RO/dI, not fine. Apparently, deionized water can dehydrate you if ingested. Bottom line is, DON'T USE TAP WATER FOR YOUR TANK, and you won't have the problems associated with it. Most of us have learned this the hard way. There are no shortcuts in this department, IT IS FUNDAMENTAL at this point.