Shannon said:

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.

It doesn't matter WHAT kH builder you use, they will all raise the pH.
Just the nature of the beast. Bullseye, pH up & down and similar
products are bad news - avoid them.

You have yet to state your kH, BTW.

There are no magic formulas that will force your pH to 7.0 and keep it
there - Period. Water chemistry is a complex series of reactions that
are constantly in ebb and flow.

With that in mind, perhaps it would serve you well to do a little
research on basic water chemistry and get it straight in your head
some of the more basic reactions. Not meaning to be a smart-ass.
You demonstrate a misunderstanding of general water chemistry.

Changing the kH WILL alter the pH - they are linked.
If you want more acid water, you lower the kH. The water will
naturally respond with a lower pH. Don't go below 2-3 kH because the
water loses it's buffering capacity. Buffering capacity is the
water's resistance to rapid chages in pH.

So, set the kH to 2-3 for adequate buffering, and use peat filtering
or CO2 injection to lower the pH if necessary. CO2 is used in Planted
tanks - if yours is not, go with the peat.

With that said, most fish are not really THAT particular about the pH
as long as it is STABLE. This is one good reason to avoid rip-off
chemicals like Bullseye - they cause constant fluctuations of the pH
level, not to mention the contents of your wallet. Work with the
water you have and things will go much smoother.

Look here for more good info:

www.thekrib.com

Good Luck,


Greg G.