On Thu, 20 May 2004 17:28:34 -0700, "simplesoul"
wrote:

Any guesses on why the PH level doesn't level off?
Thanks in advance for anything you can offer.

pH isn't a thing like chlorine or salt, but a relationship with
hydrogen ions that tell us whether the water is more acid than
alkaline. The pH is stabilized by KH ,called alkalinity hardness
carbonate hardness and probably other things but you need to maintain
about 150ppm of these minerals to be able to get pH readings that make
sense. The acid directly consumes the KH and should not be allowed
to reduce the KH below 150 ppm.

Morning pH readings before the sun rises will be lower than evening
readings because the plants consume oxygen at night and release carbon
dioxide which forms carbonic acid in the water and causes a lower pH
reading. During the day plants consume carbon dioxide and use
sunlight to produce plant food and the pH readings go a bit higher.
Fish live well in pH readings up to 9. If it isn't over 9 and the
fish are doing well, I wouldn't bother it.

I don't have a concrete pond, but others do and they have live fish
and I can't tell you how high their pH goes, but I suspect it is
higher than 7 if they have a good KH reading.

Regards,

Hal