Quote Originally Posted by The Raddish
Well, they are useful until a noobie gets the hang of how much of what to add when. Once the noobie knows how to do that though, they're useless again.
Not true, they are dangerous in the hands of a newbie.....if you follow them it is way to easy to overdose. pH adjustment is not a simple thing and is influenced by the Total Alkalinity. A LOT of chemistry happens in the water when you make pH adjustments that affect more than just the pH The Acid and Base demand tests make some assumptions as to what the TA is. IF the TA is out of range then the results are not valid. It is better to add a small amount, wait a day, retest, and add more if needed. If you keep a log of the pH and the additions and also track you TA you wil soon learn just what kind of adjustments you need for your pool.
The Acid and Base demand tests, IMHO, are only useful in the hands of a skilled technician when rapid changes in pH are needed such as an acid startup of a new plaster pool.