Jeffrey Fullerton (
Tue, 13 Mar 2001 21:34:39 -0500

> My tap water is strangely soft yet an extremely high 9.0 to 9.2 on the pH
> test kits.
> BG
I remember that when I tested the water your Elassoma zonatum came in.
Those conditions are typical of my rain barrel with a thick coat of hair
algae on the inside. This is probably because it's rain water which is
soft but poorly buffered. Yet the single bluespotted sunfish I stick in
there every year seems to thrive in this caustic environment.

Soft but alkaline- sounds like a paradox but possible when you have
poorly buffered water and lots of plant life. Plants and algae drive the
pH up when they crank out oxygen. This used to happen with my pond
before I started using pine and then barley straw. In the AM pH readings
would start out in the low 6s and rise as high as 7.4 on a bright sunny

It has been said this is not good for the fish - but surprisingly mine-
including blackbanded sunfishes have survived and even reproduced
despite these radical swings.
If you want to raise fishes that require or benefit from alkaline water
the best way to stablize the pH is to use gravel derived from limestone
in the pond and maybe crushed oyster shell. Or the same in your
biofilter. For acid loving fish use peat or pine needles or barley
straw. Both minerals or tannic acids ironically serve the same function
of stablizing pH. When using organic substances like barley straw -
which is also used for algae control - it is a good idea to remove it
from the system before it decays or else it will contribute nitrogen and
phosphates that fuel algae growth.

Jeff fro PA

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