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Re: [APD] CO2 Charts and High pH

Not quite -- well, right but not quite clear. If the buffer
is (are) carbonate(s) and (if I understand Roger's last
post) the pH is not too high (up over 8) then it's fine to
have a buffer. In fact having some buffer helps keep the
tank a bit more stable. I like to add some carbonate to my
water to bring the KH up to about 4 or 5 if I'm going to
add CO2. I learned that from George and Karla Booth's
excellent web site. 

It's noncarbonate buffers that mess things up for the
ph/KH/CO2 table.

The table works because the CO2 and carbonates work in
opposite directions on the pH. So if you know the value for
one of them *and* the pH, you can determine the amount of
the other that's present. But if something else is
affecting the pH strongly, then you'd need to use a diff
table that accounts for the affect of the other buffer --
small amounts of other buffers won't have significant
affects -- but larger amounts will. Some past postings of
Roger's were quited in The Aquatic Gardener (TAG) several
issues ago, giving the "adjustment" for one such situation
using small amounts of a noncarbonate buffer.

In the case of high pH values, no table is needed or useful
because, Roger has told us, the CO2 all gets converted to
carbonates in that situation, which I take from Roger's
post to mean that the CO2 level won't rise if you add CO2
so there's no point to try.

I hope Roger will correct any errors in the above. He
always explains these things so well.

Scott H.
--- Laser <laser at rse_co.za> wrote:
> Hi Josh
> The handy co2 chart will be null & void if you add any
> buffer. As far as I can tell the chart can only be
> accurate in non-buffered water.

S. Hieber

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