carl, From your post above: "...The PoolForum method is
1) You lower pH to 7.0-7.2--since alk and pH are closely linked and move together, this pulls the alk down some.
2) now you aerate to raise pH without raising alk as well--there are reasons why aeration raises pH but doesn't raise alk, but the chemists here can explain it in the china shop. Raising pH with Borax or Soda Ash will raise alk back--soda ash makes it even higher.
3) Lower pH again to 7.0-7.2, again pulling alk down
4) Aerate again to raise pH without raising alk.
5) keep repeating as you ratchet alk down.
6) When you hit your target, aerate to get your pH up and treat your pH normally."

From Ben's post on this (http://www.poolforum.com/pf2/showthread.php?t=191): "
  1. "Test your ALK, and record it.
  2. Decide what your target ALK is.
    If your ALK is high, due to some past dosing error, target 120 ppm, unless you have some reason to go lower or higher. If you anticipate a continuing problem with high ALK, say due to high alkalinity fill water, target 100 ppm. (These are not magic numbers -- if you have a reason, and understand your options, other values can work as well or better!)
  3. Use small doses of acid
    to lower your pH to just above the lowest value on your testkit -- or 6.6, whichever is higher. Do NOT lower the pH to whatever the lowest value on your kit is! In many cases, if you try to do so, you'll ACTUALLY end up with a much lower pH, which can damage your pool. Instead, make SURE that your pH is at least a little higher than the lowest pH value your kit shows. Also, do NOT try to lower your pH all at once; for all sorts of reasons, it's important to do it gradually!
  4. Begin aerating.
  5. Test your pH AND your alkalinity.
    Continue adding acid to MAINTAIN your low pH until your alkalinity reaches your target value.     Once it does, CONTINUE aerating, but allow the pH to rise to the normal level. (If it doesn't rise on it's own after several days, you can add small amounts of borax -- NOT baking soda or soda ash -- to bring it up.)
  6. Once both pH and alkalinity are at target levels, stop aerating."
The bold/italics emphasis in both quotes is mine.

I'm not trying to nitpick or start an argument, but those two methods are fundementally different in a practical way. In the first, you allow the pH to rise as you aerate while in the second you actively keep the pH down.