Rain Water for Planted Tank

[driftw00d]

Rain water is mildly acidic because water dissolves with carbon dioxide in the air to form carbonic acid. It also lacks dissolved minerals and trace elements that plants use.

[XnSdVd]

you can drink from a spring (provided it is not smack in the middle of a polluted area). water from a spring is cleaned and filtered naturally.

though singapore does not have much heavy industries, the air is polluted due to automotive exhaust, pollutants blown from neighbouring countries as well as other parts of the world, ...

I agree.. . but what exactly is your point?

[driftw00d]

i think some of us are trying to say that rain water in Sg may not be as suitable for planted tanks as tap water.

[tawauboy]

I agree.. . but what exactly is your point?

just correcting some points you made earlier...

....There's no difference in rain water from a spring and rain water from a industrial drain. ....
.... it's actually quite safe if the wind is blowing west since there's nothing particularly toxic in mid to east singapore. ...

[gks]

Rain water is mildly acidic because water dissolves with carbon dioxide in the air to form carbonic acid. It also lacks dissolved minerals and trace elements that plants use.

Pure H2O is very rare since water is a very good solvent that is why ultrapure water can be corrosive.

Typically, "acid" rain is formed by the chemical reaction of rain water/cloud with sulphur compounds/pollutants from industrial/vehicular pollution. The resultant sulfuric acid when formed is stable, whereas the proposed carbonic acid is very unstable and breaks down easily to water and CO2.

In any case, rain water is not distilled nor ultrapure water since the evaporated water vapours/clouds/rain absorb/dissolves/adsorb other particles/chemicals on the way up and down.