Bromine Chemistry Question

[FormerBromineUser]

Okay, I'm relaxing or at least trying my best... Here are my morning numbers:
pH 7.5
FC 2.6
CC 0.3
TA 200 but if I go as pink/red as the video shows, it's more like 220.
I took today's sample into Leslie's, and they agree with pH but say that my TA is now 120. To recap, their results were 170 initially, 150 after first MA dose, and 120 after second MA dose. Is that a fairly typical change between treatments? If so, I am going to trust their numbers for now. After adding almost 2G total MA and aeration, my TA cannot still be at 200. (I wouldn't think so anyway). After work, I am going to Leslie's and have them test TA with MY reagents and see what they get. I also think I will do one more round of acid/aeration to aim for a Leslie's TA of 100. In-The-Swim also tests with Taylor reagents and I may run there with a water sample for a third result.

[PoolDoc]

If you carry water to a store to be tested for TA, be SURE that you (1) fill the bottle 100%, and leave NO air space, and (2) keep it cool. Otherwise, you'll get a bogus result.

Chlorine, pH, and TA results are 'perishable' and will not be reliable if (a) the sample is improperly collected (air space, mainly), (b) mishandled (shaken, vibrated, etc.), (c) overheated, or (d) stored too long -- 6 hours max, mainly for chlorine.

Actually, if there's oxidizable goo in your pool -- likely during startup -- you'd almost have to 'race' the sample to the store to get a result as accurate as your home test. And if you half fill a bottle and then agitate it (rolling around on the floor, driving a rough road, etc.) the sample will be read higher in pH and lower in TA than is actually the case in your pool.

[FormerBromineUser]

Hmmm, interesting. I am going to agitate a sample at home to see if I get a lower TA reading.
Do you agree that my TA must have come down somewhat after two series of MA and aeration? You said it would be a long process but if I still really am at 200, nothing has changed.

[FormerBromineUser]

Results:
Home: No difference in TA after agitation. TA still 220-230 depending on how dark a pink-red I go for.
In-The-Swim: TA 240 and he went dark like my 230
Leslie's: First he used his reagents. TA 110, then mine TA 150. He stops when color is greyish.
So, I will trust my reagents and just be frustrated that there has been no change in TA after 2 full cycles of MA.

I think I may have figured out my problem, however. Even though I read the directions over and over.... I goofed and am feeling pretty embarrassed.
Your instructions say:
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.
I have been getting my pH down to 7.0 and then aerating to bring it back up to 7.5/7.6 and then lowering it back to 7.0 and aerating back up to 7.5/7.6. I see that your instructions say MAINTAIN low pH. I am now going to keep it around 7.0. I will reduce the amount of aeration at least until I know the MA has completely circulated.
Does that make sense? In the meantime, should I continue with 1C dichlor every night or switch to the calcium hypochlorite?

[PoolDoc]

I'm going to have to give you some different instructions.

1. Test your pool's pH each evening. If it's above 7.2, add 1/2 gallon of MA. Make sure the pump runs for at least 4 hours after. Do NOT test TA or CH during these 3 days!!! Continue to aerate, using whatever approach you've chosen.

2. After 3 evenings of testing pH and adding MA **as needed**, the following (fourth!) day test the TA.
==> If the TA is <150, do not add acid for 3 days. Do *NOT* test the TA again for 3 days. Discontinue acid additions during this period.
==> If the TA is > 150, recycle to #1 above.

3. After waiting 3 days (after a TA reading < 150 ppm), retest both pH and TA, and report results here. Do NOT test either pH or TA during the 3 days you wait.

OK?

Under NO conditions should you ("BromineUser") test TA more than 2x per week.

[FormerBromineUser]

I think I've got it.
Maybe you'll have to add these instructions as an addendum to your original. I'm thinking "Lowering Swimming Pool Alkalinity ...FOR DUMMIES" Feeling pretty low and incompetent right now!
In the meantime, I have been using 3/4-1C dichlor nightly. Do you recommend I use dichlor or the calcium hypochlorite (or a mixture) during these next many days?

[CarlD]

Let me try to simplify the T/A lowering procedure. We've batted this around for at least a half-dozen years until Chem_Geek untangled it so we all understood.
1) T/A reading depends on the pH reading. So at 7.0 you'll get a lower T/A than at 7.8, when actually they are linked. If you raise pH with Borax or Soda Ash, T/A goes right back up.
2) So you lower pH to, say, 7.0.
3) Aeration RAISES pH! The fancy chemistry has something to do with breaking down carbonic acid in the water but the end result is aeration raises pH but does NOT raise T/A with it, unlike other ways to raise pH.
4) You then lower the pH again, pulling down T/A with it, and aerate to raise pH without raising T/A again.

In other words, you are ratcheting the T/A down. The aeration doesn't lower T/A (though if you keep pH constant at 7.0-7.2 it will SEEM that way). Lowering pH lowers T/A and aeration allows pH to rise without raising T/A.

On another note, you keep wasting your chlorine reagents doing the 25ml test. Only do the 10ml test. We/you don't need to know that FC is 7.2 or 7.4, 7.0 or 7.5 is close enough. Same for CC.

[FormerBromineUser]

So if I understand you, my lowering pH with MA to 7, raising by aeration to 7.6, lowering by MA to 7, raising by aeration to 7.6, etc., actually might have done something other than waste time and MA. I don't feel so stupid, if so. I think though that Ben is saying that I need to KEEP my pH low for an extended period and not to aerate with the goal of raising pH all the way back up to 7.6 or higher before adding more MA. I will follow his instructions to the letter as my ultimate goal is to have a great pool with no unneccesary chemicals, to keep money in my pocket and not the pool store's, and to become "FormerBromineUser"!!!

[PoolDoc]

Feeling pretty low and incompetent right now!

It's not that at all. People are wired differently. A couple of years ago, my Assistant Scoutmaster was that way. We were accumulating more and more gear, but couldn't get permission from the church to build storage shelves and racks. So, the stuff piled up. It didn't bother me: they were somewhat organized piles, and the boys could not have cared less. But David is neat and organized by nature, and it drove him nuts. In truth, he was rather obsessive about it. But, that same nature had enabled him to pay meticulous attention to mind-numbing financial papers, with result that even though he was just over half my age, he could buy and sell me 10x over.

There are times when it pays to be obsessive about pools, but this particular situation of yours isn't one of them.

[CarlD]

I think there's come a time to all of us when we say "D*** it all! I'm going to empty this pool and shut it down! No more!" Sometimes more than once......

It reminds me of the cynical quip: "A boat is a hole in the water, surrounded by wood or fiberglass, into which you throw money!" With the follow-up being "The two happiest days in a boatowner's life is the day he buys the boat...and the day he sells it!"