The pH is really a good indicator of the stability of the pond, which is
maintained through buffering. The measure for the amount of buffering is
the KH carbonate hardness test. I like to have my hardness at about 10
degrees, while a minimum would be about 4 degrees. To boost the KH, use
common Arm & Hammer baking soda. Your filter bacteria rely on carbonates as
part of the food and consume quite a bit. You can also use oyster shell or
limestone but the dissolution rate is so slow that I don't think they can
keep the pond stable.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Weldon Wallick" wrote in message
...
I got a test kit and my pond has a pH of 6.5. Everything else is OK.

How can I get the pH to the "desired" level (7.2 or more) and keep it
there?

Aquariums do the same thing here - Central Florida.

The water is hard and alkaline, but swings over to the acid side.