Did you mean algicide?

Yes. blush

I'm not sure. The math is too hard for this time of day, but intuitively it
seems to me that if your pH is low enough to protect the fish from ammonia

Very often the thing that has happened to newbies, that have had a pond for
awhile and have escaped anything serious, suffer a filter crash, because
they haven't been monitoring or maintaining their ponds correctly. This
drops the pH (as Ingrid mentioned the organic load, and the drop in
buffering) and the ammonia builds up, but isn't toxic due to the low pH.
You change 50% of the water, the old ammonia & new off the critters, is now
toxic as the filter is still not working. This has happened often enough
now that thru the KHA program we are not to suggest a water change till we
know what's going on with the water. The KHA program is much like the
Master Gardener program, you can't just shoot from the hip, as people can
come back and sue. Obviously there is protection in usenet, as they would
have to track you down, but still not responsible. So....

you couldn't worsen the ammonia toxicity.

Yes, you could. I've had it happen.

However, if you're using municipal source water, these days, you almost guarantee that
every water change adds ammonia.

And thus, if they have Amquell or equivalent added to the water prior to
the change, then make the change. At least we won't kill or stress the
remaining critters.

We still have to figure out why there is a problem and people aren't going
to get away without having test kits, unless they belong to a club and have
a KHA they can drop water samples off with. Best friend is okay too, but
KHA's (in my local club's case) test kits are paid for by the club. ~ jan



~Power to the Porg, Flow On!~