[Sapphire Window Cleaning]

wouldn't use it in fish tanks unless you add essential minerals.  

You can buy pure water, from aquarium shops, for marine fish tanks

You will have to an vitamins to the water, but personally I use 70% RO and 30% tap water for my tropical fish tank.



Matt

[Sapphire Window Cleaning]

You also have to make sure the PH isnt too high or too low, my pure water has a PH of 5 and my tap water has a PH of 8




Matt