Rain Water

[orion57]

just a quick question, why do some people say fresh rain water is ok to put in tropical fish tank
and some say no.

 

[mattlee]

i think it depends oh where you live.
if you live in a highly industrial area then your rain water will/can be polluted. on the other hand if you live in the rural countryside with no industry nearby then your rain water will be much much cleaner.
i suppose also it can vary in pH value.

 

[OldMan47]

Rain water is fairly low in mineral content so it can only be used like RO water to mix with tap water and reduce the mineral content. It is far too pure to use without adding in minerals from somewhere. I always let the rain fall for a while and flush out my gutters before collecting any. That way any contaminants in the air will have been washed out and anything on the roof or in the gutters will also be flushed out. I end up with water that measures only about 8 ppm of TDS content while even my RO water runs close to 20 ppm. Tap water where I live runs closer to 225 ppm of TDS so either rain or RO will dilute it fairly well.