Water Quality

I believe I have a serious water quality problem, and it is causing some of
my fish to die, 14 in the last few days: here is the problem:

I have a 3,500 gall pond, stocked with about 70 fish of varying sizes (3" to
26"). Almost all the fish are huddled at the bottom of the pond in one area,
and they are slowly dieing with a range of diseases.

I have checked the water quality and here are the results: PH 9.5, Ammonia
0, Nitrite 0, Nitrate 0, Temp 5C. I have a very good filtration system
running, which does a complete water change every 3 hours. Water is crystal
clear. There is some algae bloom on the surface, which is unusual at this
time of year.

9.5, wow. I think that would be enough of a stress right there. What is
your KH, have you checked the pH in the AM & PM? Why do you think the pH is
so high? New cement?? Need to know what is causing it to fix it. ~ jan

~Power to the Porg, Flow On!~