"MJB" wrote in message
. net...
I originally went to RO because my tap water has a pH of about 7.6. I
made
the switch before I put in the CO2. Never considered going back to tap
water.

If your pH is only 7.6, then your KH is about 4-5 degrees, not terribly
hard. As others have pointed out, you should only use CO2 to lower the pH.
In addition, reconstituted RO water is not as good for plants as tap water
of the same hardness. It would statistically have a greater variety of trace
elements and good amounts of both Ca & Mg, which plants like in high
quantities. I don't see any reason why you should spend the extra effort on
RO anymore. You can easily maintain a 6.8 pH with CO2. Don't add any buffers
because they'll throw off your CO2 calculations and defeat the function of
CO2 of reducing your pH.

pH stable claims to not contain phosphates. I do have a history of
higher-than-one-would-expect phosphates.

That's good. Plants like PO4.
__
Alex
pcalex (at) hotpop.com