"Joan" wrote in message
...
The pH comes out of the tap at around 7, but the alkalinity is
approximately zero, so I have no buffering capacity unless I add some
buffer. I try to keep the alkalinity at around 100.

I'd prefer that the pH be a little lower than 8.5, by the time I've
gotten the water suitably buffered, the pH is up. I use the
commercial product "Buff it Up" for ponds. Dissolves nicely and
doesn't cloud the water, and keeps the alkalinity up for longer than
sodium bicarbonate. The pH stays nice and stable, varying hardly at
all from day to day, and even not varying much from AM to PM.

I do get a lot of string algae in the pond, which I take out as I can,
but it keeps on growing. I don't mind it as long as it doesn't get
too carried away. But I suspect that it pulls a lot of CO2 out of the
water during photosynthesis, which pulls the pH up by the end of the
day. I do make it a point to keep the submerged algae under control
so it doesn't drive the pH up too too high by the end of the day.
================================
For buffering have you tried something more natural like oystershell chicken
grit or small limestone rocks? I found neither one raises the PH much but
does buffer the water and keeps the PH from dropping. Both keep the water
above 7.
--

RM....
Frugal ponding since 1995.
rec.ponder since late 1996.
Zone 6. Middle TN USA
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