First I want to thank everyone for their replies. To clarify....

I have poorly buffered water from the tap (not RO, maybe my kH is low?) and
an unstable pH which tends to drop (presumably from mulm buildup in the
gravel). My substrate is kind of deep (4-5 inch) but I do keep regular 3-4
week 33% water changes. I need to breakdown the tank and clean out the
gravel (been set up~4yrs) but also want to start buffering the water to
maintain a stable pH. My issue with baking soda is that the pka is
somewhere in the mid 7's if I remember correctly. This would mean it is not
much of a help as a buffer below pH 7 where my fish like it. I may have
this a little confused but the principle is there I think. If I add sodium
bicarb my pH obviously shoots up above 7 but doesnt tend to stay there too
long. Just curious if there are any commercial preparations that will keep
the pH around 7 or slightly under with no phosphates in them. The bullseye
I added doesnt state either way but I am starting to see some hair algea so
I have my suspicions.

again thanks for everyones help,
John


"Pittie" wrote in message
...
Recently learned that my water is soft and is contrbuting to an
unstable pH. Just wondering if anyone knows of any good buffers on the
market that dont contain phosphates. Most dont list the constituents.
Thanks for any info.

John


PS I dont really want to mess with baking soda due to poor buffering
capacity at pH values below 7.