Here are some good articles to read:
Low pH causes and cures:
http://www.reefkeeping.com/issues/2004-09/rhf/index.php
High pH causes and cures:
http://www.reefkeeping.com/issues/2005-03/rhf/index.php


Bubbles are nasty because when they pop the spray a tiny amount of salt
water straight up and your light covers and any near by equipment gets
covered in salt. Also, if you have a functional protein skimmer going
that will do a fine job of aerating your water for you with millions of
little bubbles that in a properly designed skimmer will not get into
your main system.

Blake.

Wayne Sallee wrote:
No you don't want air stones in your salt water tank. It
is true that aeration drives off co2, thus raising the ph,
but what you want, is to add some buffer to get the ph up.

Wayne Sallee
Wayne's Pets



wrote on 11/4/2006 10:30 AM:
I everyone, I'm new here and I do plan on adding all my tank info in
the next topic but for now I just want to know why an airstone is
recommended in a reef tank to raise the PH but I've so far never seen a
pic of a tank with bubbles in the background. I have problems with my
PH and have read several articles in this group regarding this problem
and lots of answers revolve around an airstone, does it go in the main
tank or in the sump?
Louise