How to clean hard water stains from glass aquarium?

Question

In aquarium stores I have seen that the fish tanks are always clear without any hard water(salt) stains.How to effectively clean the stains?Can I use soft water(drinking water) to it or will the fishes die?I have two small black color sharks and one dalmation mollie.Even if I clean using vinegar stains reappear within 3 or 4 days.

Answer 1

If your water is that hard, and you are keeping fish that prefer a lower pH, then RO water is the best thing to use. However if you are keeping fish that thrive in higher hardness, you might not be able to do much. In my area the pH is 7.7, KH is 13. If I wanted to lower it to say 6.0, I would probably want to mix  ratio of 60-75% RO to 40-25% tap.

Answer 2

i use RO/DI water (essentially the same as drinking water) cause i have it on hand for my SW tanks.. doesn't leave streaks or water marks and clears salt away without streaking as well

it can be found at most fish stores nowadays, especially ones that sell SW fish.. it's pretty cheap too, 50 cents a gallon, just buy a gallon and fill a squirt bottle occasionally to clean off the glass