The pH can be as high as 9 without being a problem for the fish. The
important thing is to have it stable. Check the pH first thing in the
morning, and last thing in the afternoon and see how much it changes. The
problem with the pH lowering salts and chemicals is that they consume the
carbonates that make the system stable. I don't worry about my pH, I try to
keep my KH carbonate hardness above 100 ppm to assure stability. It causes
my pH to generally be in the mid 8's. The carbonates are used by filter
bacteria to convert the ammonia and nitrites, and if it is spent, then the
filter stops working.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html

"Brendan" wrote in message
ups.com...
It's quite murky, so I can't tell if they're there or not.

I just checked pH and it looked like 8.2 (ouch) so I put in some pH
reducing salts. It's supposed to be 7-7.6, right?

It's about 500 gallons, by my estimate. At the moment I only have a
little pump that circulates water down a very small waterfall. Should
I get a filter as well?

thanks