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Hal[_1_] · 15-05-2007, 03:22 PM posted to rec.ponds.moderated

On Mon, 14 May 2007 08:35:20 CST, wrote:

OK, I went back and did a search. This message was from Rod Farlee
who IS a chemist. this is what he said on 6/16/1999
Ingrid

"But this "pH pill" is not the "one size fits all", "toss it in and
forget it" remedy that the ******** suggests it is.

It certainly works, but with some caveats. It raises GH (general
hardness, calcium) more than calcium carbonate (limestone) alone
does. That's because it contains calcium sulfate (gypsum), which
is much more soluble than calcium carbonate, and which raises
GH but not KH (alkalinity, bicarbonate).

So unless one has very soft, slightly alkaline water to begin with,
care should be taken. GH and KH should both be monitored.
If GH is getting too high, take it out, and add baking soda if needed
to raise KH. Or limit the amount to less than 1 lb/1000 gallons, to
ensure GH does not continue to rise.

Thank you Ingrid!
I'm sorry if you had to work a bit harder than you wanted to, but I
appreciate the information.

It is more a mystery now, more than ever as to why I got higher KH
readings after putting plaster of Paris into my pond, if it only
raised the GH, however I shall consider this a lesson learned.
(Not universal)

Regards,

Hal