Are sequestrants required? I had a major scale problem to resolve and don't want it to come back.


Mar 27, 2019
Jacksonville, Florida
Hi All,
I recently removed scale buildup in my pool and absolutely never want to go through that process again.
Is a sequestrant required or recommended if you're keeping your water balanced to TFP recommendations?
The pool was re-plastered last April with CL Industries Sunstone Pearl (St. Lucia). The summer was a sad comedy of errors following the local pool store advice, leading to my scale problem.
I was able to figure it out with information from this site and now simply nod and smile when the pool store tells me I need to do X,Y, or Z. I let them check it when I go in to buy liquid chlorine or acid.
The pool is now in full sun (removed enclosure) and gets very warm (86 today, hit 94 last summer). The pool store had me at the top of the ranges and never asked about temperature.
We fill with well water (150 hardness) using a Hayward sock.
I'll get on a sequestrant program if needed. I'm using some that's left over from the scale treatment right now.
Pictures attached for reference.
Thanks in advance.


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
We need to know all your test values to know if you're truly in good shape-
Salt (if you've got a SWG)

You are doing your own owner testing......right?? With one of our recommended test kits?? This is seriously important to protect your investment.

Your pool needs a certain amount of calcium to protect the plaster. But it isn't just calcium that determines if your water is aggressive or balanced. It is a combination of all those above tests which help determine the quality of your water.

Maddie :flower:
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Mar 27, 2019
Jacksonville, Florida
Yes, doing my own testing, except for Total Chlorine right now. It'll be two weeks tomorrow that I put in the Jack's Magic #2 product. They say it shows a false FC for 3-4 weeks and to use Total. I have the Taylor K2006 FAS-DPD kit.
My test results earlier today were:
FC 1 with a Total of 3 (pool store results) I added enough liquid this evening to bump the total to 4. Other than during the scale treatment, I've been maintaining a FC of 7.5 to 11.5% of CYA since ditching the pool store advice..
CC 2 (pool store result). Normally I'm at 0 and have only shocked with liquid chlorine once it got to 0.3. I've yet to SLAM, but that's coming.
PH 7.5
TA 80
CH 290
CYA 35
Temp 86
22 year old pool running a new sand filter and no SWG.
If it's possible, I'd like to save the expense of the sequestrant. It was about $200 in product to treat the 22,500 gallon pool for scale. Thankfully, I work from home and was able to stay on top of it.


Mar 27, 2019
Jacksonville, Florida
I opened another tab and have been reading the link and beyond into Calcium Scaling (Thanks).
I've yet to use the poolmath tool, but will here shortly also.
The test kit came with the Taylor "Watergram". Between it and reading on this site, it was a real eye opener once I got a thermometer and started using the pool store test results last year.
I had CSI numbers of 0.5+ most of the summer.
Gotta love those pool stores. They sold me plenty of product..... :-/


Mar 27, 2019
Jacksonville, Florida
If I'm diligent and keep the water balanced, with the CSI in range (using the app calculation), would it be ok to proceed without using a sequestrant then?
The product I have left over and am using is Jack's Magic Magenta Stuff. I thought the scale removal process would take longer and bought two extra.
With the cost of the product and adding 10 oz a week, the program would add another $360 a year to my pool maintenance.


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
I can't see why not. I manage my CH up to 1000 ppm without scale. We have other members that do it up to 1500 ppm CH with aggressive measures. All by managing CSI.
Sequestrants mask the issue. If they dissipate and you do not catch it, the scale will come in a vengeance if your CSI is too positive.