"Peter Smith" wrote:

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").
That seems like a lot of fish.

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.
What kind 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.
What is the PH from the tap? If it's a lot lower I'd do a water change. I'm
not sure your good bacteria are working at that temperature.

Now I believe that my problem is caused by the low temp coupled with the
high PH is causing some kind of ammonia poisoning even though the reading is
low.

What do others think and if it is a PH problem, how to I reduce it?
Well, that ph is high, but it's hard to imagine that would kill that many
fish. Others may have better knowledge about ph than I. Is it possible that
some pesticide has entered your pond, perhaps from runoff or a neighbor
spraying? I would do a water change - can't hurt, just remember to
dechlorinator it.


San Diego Joe
4,000 - 5,000 Gallons.
Goldfish, a RES named Colombo and an Oscar.

"We need to make a sacrifice to the gods, find me a young virgin... oh, and
bring something to kill"