Acid and Base Demand tests: Useful or Not?

[CarlD]

Evan,

Remember: we are primarily working for what works easily and practically for home pool owners.

What problem do acid and base demand tests address than cannot be easily dealt with without them? And are those particular problems common or highly unlikely?

If my pH is high I can use a gradualist approach of adding Muriatic Acid to bring it down.

If my pH is low I can use a similar approach by adding Borax to raise it.

How much easier do those tests make these tasks?

If a pool owner can handle all of his/her issues both when the pool is clear and when there is a problem, without acid and base demand tests, then they are NOT particularly useful for that pool owner. That's simple logic.

Not every tool is necessary for a home-owner.

Carl

[BigDave]

Could the Acid / Base Demand tests be useful to our friends that are reading at either end of the comparator to get a handle on how far off the scale they might be? Should one drop bring the color onto the scale, they're close; Several drops could indicate a more urgent situation. Just a thought.

[PoolDoc]

Guys, I think you're losing track of the OP. Carl, Waterbear . . . if you want to discuss the relative merits of using or ignoring the acid / base demand test, please open a new thread in the China Shop. Personally, I always ignored it, because I have long preferred the little dose, retest and add another little dose approach. But, I never had to work with residential pools that had been mega-over-dosed with acid or soda ash.

Still . . . China Shop, please.

Thanks,

Ben

[waterbear]

China shop is fine with me. Carl, care to split the thread? Post 9 seems to be the place where it went south.
And to answer your question, acid demand test is VERY useful when lowering TA.
Only time I ever had to use a base demand is when someone was not paying attention to their pool chemistry and was using trichlor and had a pH/TA crash and that is rare but I do use the acid demand test all the time.

[CarlD]

Evan,
I'm always open to new ideas. Tell me how to use the acid demand test (I mean, other than directions) and what I can hope to learn from it. Is it REALLY that needed beyond a gradualist approach?

Carl

[PoolDoc]

Evan;

My take on AD & BD tests is that they can provide information someone might LIKE to have, but --- major overdose correction situations aside --- there are few (if any) cases where they provide information someone NEEDS to have.

For example, if you want to lower alkalinity, an AD test will be able to help you estimate how hard that's going to be. But, from a PF 'answer' point of view, what rookie pool users need to be told is STILL "hold your pH to 7.0 or just below until your TA drops to an acceptable level". Functionally, they need to do it however long that takes, and knowing that it might be a long time, doesn't modify the process.

So, as I see it, the AD test adds (to use an awful neologism) "non-actionable" information. You 'know' more, but you can't DO anything with that knowledge.

Granted, it might help with some of the 'Nervous Nellies' or OCD types that show up here. But my experience is, in dealing with OCD's that there is NOT a level of information that actually relieves their itch. No matter how much you tell them, they still want more.

However, if you tell them too much that's not "actionable", this new (and functionally useless) information confuses them or distracts them from paying attention to the USEFUL information, like how low their FC level is.

Anyhow, that's my opinion. But, I'm open to correction.

Ben

[chem geek]

When lowering the pH in my pool, either just to get the pH lower or when doing the TA lowering procedure, I have a choice. I can calculate how much acid I need to have accurately using my spreadsheet or I can use the acid demand test in my Taylor K-2006 kit. I've done both, but over time, I tend to just use the acid demand test because it's there and it's easy. Eventually though, I just know how much I need to add (for regular lowering of pH, that is).

The other time the acid and base demand test is useful is when one is unsure of the pH reading. The acid and base demand tests let one move the pH color up and down to see where the pH might have been. I did that in the early days until I got used to the pH test though now I don't see the need for it anymore.

[PoolDoc]

I just realized something.

Carl (and I) think about A/B demand testing from the point of view of trying to teach newbies to use the test, adjust with small doses, test again method ("the TATA method"? ) . . . AND keeping the NUMBER of things tested and taught to a minimum. If a newbie follows the TATA approach, they'll never (or almost never) need the A/B test.

Some of this comes from my background, controlling pH in commercial pools with acid feed, rather than slugged doses.

Evan, you have worked a lot with pool store walk-ins, where you are FORCED to use a large 'fire and forget' doses, because you have no idea if they'll come back. In THAT environment, A/B testing would be almost essential.

And of course, Richard instinctively approaches pool testing from the "how can I acquire the greatest possible amount of analytical information about my pool's water"? Obviously, A/B testing would be a component in that.

So I think what's happened here -- in part -- is we were all speaking from different perspectives, without noticing it. So, now I'm trying to 'notice it'.