On Tue, 8 May 2007 13:00:33 CST, Joan wrote:

The stuff I used is called dolomite lime. It contains mostly calcium
carbonate and magnesium carbonate.

The pH has been fairly stable from day to day and is ranging from 7.5
in the AM to 8.5 at the end of the day.

Unfortunately that isn't stable. Your change should only be about 7.5 in
the AM to a max of 7.9 in the PM. The problem is your low KH/buffering, as
you mentioned, not the plants. This is also why the algae is blooming and
why the mud is not settling. Get the KH/buffering up and things will settle
down/out.

What is the KH of your tap water? If that is good, do a slow flow thru if
you can, otherwise 10% water change every other day will not hurt the
balance.

A flow thru system, with carbon filters on the new water, is being highly
recommended in the koi community right now. Where about 10% exchanges over
a 24 hour period. This isn't for everyone, especially if your tap water
isn't great, or water prices are high. It's more a high-end koi keeper's
ideal. I personally have an accidental flow thru, some small leak that
drops the level about an inch/day, so I add water when I get home.... I'm
still doing a 20% on the weekends.

IMO, I'd be using baking soda to get my KH up. About 1 cup/1000 gallons and
retest. That pH swing is harder on your fish and filter than adding baking
soda. ~ jan
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Zone 7a, SE Washington State
Ponds: www.jjspond.us