"jrock64" wrote in message news:61_wa.612891$Zo.133366@sccrnsc03...

I am using Aquarium Pharmaceuticals Dry Tab Wide Range PH test kit.
Range 5.0 - 9.0. My fill water comes from a 12ft deep sandpoint(very high
water table) PH 8.5. My 1800 gal pond runs a PH from 8.5 to off the scale.
During the summer off the scale occurs about every two weeks at which time I
add 1/2 to 3/4 cup of muratic acid to a 5 gallon pail that drains into the
pond through a small hole over a 1/2 hour period.

This suggests to me something in the pond is raising the pH.

My pond design does have a lot of cement blocks
inside of the pond but I would have thought that would no longer be a factor
after a year.

cement blocks will react with Muriatic acid. The acid will eventually
dissolve the blocks. In fact, I think the blocks are most likely the
source of your alkalinity. I would seriously consider covering them
with a plastic liner of some kind. Then the water will most likely not
change radically from the 8.5 it started at. Having to add Muriatic
acid to a pond indicated something is radically wrong; there is a
major source of alkalinity in there somewhere.


See my semi formal pond at http://photos.yahoo.com/jrock64rose

It is quite lovely.