Does anyone have any experience with this sequestrant test?

[poolcool]

LaMotte Phosponate Test Kit, Direct Reading Titrator, 0–20 ppm/4 ppm HEDP/PBTC, 50 Tests

There were some posts way back when that indicated some concerns about clouding due to a "small overdose of the most popular stain and scale control chemical ingredient, HEDP".

You can read them here:

hedp-overdose-and-clouding-t12982.html

I still have some cloudiness after raising my CH from 150 to 300, then doing a citric acid cleaning and subsequently adding a lot of HEDP within one week (about 4 qts in 20K gals). The directions are 1 qt per 10,000 gals for first treatment, then 2-3 ozs per week maintenance, but the acid treat procedure implies that more is better than not enough.

Other than polyquat type algaecides, I don't what other pool chemical can't be tested adequately and economically. It's like flying blind.

 

[JasonLion]

Have you rules out the obvious possibilities first? Make sure you wait a week after adding sequestrant before worrying about clouding. And second, are you sure you don't have algae? If neither of those apply, I would try some clarifier.

 

[geekgranny]

People say that doing the AA treatment doesn't affect scale. Maybe it doesn't but after doing it last fall I kept HEDP in the pool all winter at higher dose than called for and pH 7.2 running the pump and cleaner all winter till early Feb. when I closed down the pool for our unusual Big Freeze.

I kept two submersible pumps running, keeping the water circulated and ran the Aquabot for many hours a day for two months after that because I went ahead and took the pump and filter out of system and didn't get the new pump and filter in for a while. The second month I attached two big Slime Bags to the hoses putting water back into the pool and did catch a lot of the powder clouding the pool and had several very fine bags for the Aquabot that I changed out several times a day.

After the AA treatment, this was the first time I had ever used sequestrate. Scale kept lifting all winter. I have blue plaster so I can see where the white scale is lifting. The water kept getting cloudier and cloudier over time and I couldn't keep the fine Aquabot bags emptied fast enough because of clogging with the fine calcium.

It took the new pump and big 80 sq ft filter over two weeks to clear the calcium out of the water. In my case it was not algae as CYA and bleach levels were on or above target all winter and into spring. (I haven't had to shock since starting BBB last summer.)

I know this doesn't prove that I had cloudiness from just the sequestrate but what I'm wondering is if the same thing, calcium scale lifting off, is happening to your pool.

How old is your plaster and do you know if you had/have calcium scaling? That could be part of it.

The best advice I got was to keep filtering on a low flow, ~20 gpm, and to not brush or vacuum the pool until it cleared. As I said, it took two weeks with big filter using Fiber Clear media, that filters finer than DE.

gg=alice

 

[chem geek]

The Ascorbic Acid (AA) itself won't affect scale, but metal sequestrants including HEDP certainly help to reduce scale as they bind some to calcium, not just to iron and copper. This is why many such products are "metal and scale" removers. The ones that focus mostly on removing metal more strongly bind to iron and copper, but they still have some effect on calcium. It's just a matter of degree.

 

[poolcool]

Thanks for all of the responses.

I realize that cloudiness is not an easy issue to resolve because of the very many possible causes. I’m therefore trying to troubleshoot by process of elimination and was wondering if there was a decent sequestrant test kit so I could rule out a sequestrant overdose. If anyone knows of one, please let me know.

I don't believe that 4 qts of sequestrant in 20K gals over the period of a week would be considered an overdose because the directions are 1 qt per 10,000 gals for the initial treatment. I would then have a 2 times dose and there is a post near the bottom of the following topic that indicates that up to 5 times and even maybe up to 10 times doses should not be a problem.

metals-and-sequestrants-warning-long-post-t21040.html

I also don't think that I am getting an algae problem because I used some polyquat during the week and a gallon of 10% HTH Algae Guard (linear quat) soon after the acid treatment. I've also been adding bleach everyday as well as running the pump 24/7 with the SWG on. There is also no evidence of algae such as slick sides.

The FC is still getting consumed probably by the acid and maybe the other algaecides. I used 10 lbs of citric which I now believe to be too much. I will start out with 5 lbs overnight if I ever have the need for another acid treatment.

The pool clouding is slight so I'm trying to be somewhat patient, but my main concern is to not make it worse by the incorrect addition of other chemicals like sequestrant. At the same time, I don’t want the stain problem to return either.

A minor foaming problem has also developed which I believe may be associated with the Algae Guard. I guess this could contribute to a cloudy water issue as well.

I have some HTH Super Concentrated Clarifier but I'm a little reluctant to use it without knowing the cause. Then again, maybe that's what it's for. If I knew the cause I probably wouldn't need the clarifier.

 

[chem geek]

HTH AlgaeGuard 10 is 10% Quaternary Ammonium Chloride “Quat”, aka as a linear quat. All linear quat algaecides are known to foam which is why the only algaecide we recommend using is PolyQuat 60 which does not foam, though even then such an algaecide is only rarely needed.

The foaming will dissipate as the chlorine breaks down the algaecide over a week's time. So yes, part of the chlorine demand can come from the algaecide and some may be from any remaining reducing agent (ascorbic or citric acid).