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re: pH of RO water



>Question 1: My tap water is pretty much crap for growing plants.
>Its got a pH of about 8.6-8.8 depending on when I measure it.
>Its also hard as nails.  

Your tap water may have a high pH because the treatment process has
removed all the dissolved CO2.  Since you have hard water, the treatment
plant may be softening your water a bit to help reduce scale buildup in
pipes.  They generally do this by raising the pH and precipitating out
some of the Ca and Mg.  At this pH, all the CO2 changes to carbonate,
CO3. 

An easy way to check this is to aerate a bucket of your tap water for 48
hours.  If the pH drops to 7.5 or so, then it is the removal of CO2
that's causing a high pH at the tap.  Aeration sure is a lot cheaper and
easier than RO.  For faster results, try injecting CO2 into straight tap
water, and see what the resulting pH is.

There's nothing wrong with hard water for growing plants.

Regards,

Mark