Acid and Base Demand tests: Useful or Not?

[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]

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.

Yes. I'd forgotten about that one, but I've used that on occasion as well. And, that is a valid use.

The other issue, of determining how much acid to add, from a PoolForum point of view (what to tell newbies) rather than a personal view (what I might myself do), I strongly prefer a standard dose of acid or base, followed by a test, followed by a re-dose.

Among many other things, I think handling it this way is easier to learn and tends to indoctrinate newbies into the need to manage their pool on a regular basis.

[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'.

[waterbear]

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.
And in the process some of them get very frustrated since it takes so long and they go back to the pool store for their "miracle in a bottle"! Most pool owners, as you well know, do not have a lot of POP. If we have a tool at our disposal (since newbies are now getting the Taylor kit with the demand tests in them so they have them) to shorten the time why not instruct them to use the test when it is appropriate (such as the example I gave above in lowering TA, which is a common scenerio)?
Some of this comes from my background, controlling pH in commercial pools with acid feed, rather than slugged doses.
And this I more than appreciate since I also worked at a commercial facility with acid feed pumps that needed to be adjusted in very small increments. However, since we did test the water 3 times a day in each of the pools, hot tubs, and play areas we had a LOT of data for making the adjustments! Are we expecting the same from a home pool owner? I know I don't want to test MY pool three times a day or more to get the pH where I want it. If I have a 'ballpark amount" to get me very close that would be much better! I can then make whatever small adjustment (if any) is needed the next day.

FWIW, there are times when the TATA (test, adjust, test, adjust) approach is the only way such as with SWCGs when the owner is trying to adjust the cell output to maintain a specific FC level.
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.
However, I was using Demand tests way before I did the pool store gig. I was the one who dug the demand tests out of storage so I could use them. No one else in the store knew what they were for. They just did the computer read out and handed it and the attached shopping list to the customer!
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.
You seem to forget that I have a similar chemistry background to Richard and tend to do the same with my own pool. Then there is my many years worth of experience with reef aquarium keeping and water testing which is not that dissimilar to pool testing in many ways.
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'.

I just think that blanket statements like 'demand tests are useless' are not beneficial (and I drank that koolaid when I was trying to help 'someone' promote their testkit business even though in private conversations I suggested including demand tests because they can be useful. However, this kit was being modeled (an exactly copy?) after another kit that had been available and this 'someone' wanted their kit to be the same. I agree that the demand tests can be considered "advanced" but we do have many users who "graduate' to that level quickly.