Acid and Base Demand tests: Useful or Not?

[waterbear]

Wow, this is the first time I looked at this thread. Three pages on whether the acid/base demand tests are useful. My two cents (and that is probably generous on what its worth). I never use it on my pool. Add a little, wait add some more. But on my spa, it is quite useful, particularly the acid demand reagent. An extra tablespoon of acid can cause a drastic overshoot. I find that the test brings me very close to a desired result.

I agree, for a small pool or a spa they become much more useful since the danger of overdosing is much higher!. I am working on the second draft of a howto and will email it to Ben once it's done. Hope to get it done over the next two weeks since I just started my Xmas break from work.

[polyvue]

Yes, picking up an old thread... haven't been on in a couple of years (my excuse).

I ignored my kit's AD test for several years, relying upon Pool Calculator dot com or my own hybrid spreadsheet (calcs ripped from a perfectly good 2007 TFP post by chem geek, and bolstered by results generated by the Taylor watergram and industry LSI tables - I guess I'm what PoolDoc referred to as an "OCD" guy) to determine the right dose of MA.

Last year, I fashioned a hybrid test kit using a Taylor midget comparator (K-1285-2 phenol) and R-0853 ADR and leftover parts from old CYA (9193/4) and salt (K-1766) tests, and discovered that a drop or two of acid demand reagent helped me to validate my color-matching acumen. It's not always easy to tell 7.9 from 8.0 or 8.1 but the ADR drop took the color out of deep purple and into a range I could see without plugging in the daylight lamp.

So, my "vote" is with waterbear on this one; though I appreciate Carl and PoolDoc's (and waterbear's) concerns regarding newbie testing. If I continue to post here, I promise to attempt to answer new poster enquiries with consideration for what has already been discussed.

[PoolDoc]

I understand that the acid / base demand test can have value under certain conditions. But if you want to know the difference between 7.8 and 8.0, reliably, a calibrated pH meter is a better option.

It's also true that, if a pool's pH is out of range, the ABD test can allow you (well, us) to get a handle on whether 'this newbie pool' needs adjustment, or needs panic treatment to minimize damage.

But, I do wish that some of the tests -- and particularly that stinking Taylor manual -- came with a seal that said, "Open only under direction from PF mods or team members."

[CarlD]

I still have not used the ad or bd tests. I think once you get into a rhythm with B-B-B you tend to have less problems every season. I have backed away in my mind from "useless" to "only needed when there is a big problem with pH"
Carl

[waterbear]

Ben
I have a why, when, and howto on on the demand tests about 3/4 done. I will have more time after this Wednesday to try and finish them up and mail them to you. Right now it is rather long so I want to try and simplify and shorten it some more.

[PoolDoc]

Thanks.