Calcium Scale Removal in SWG Plaster Pool with Spa and adding Borates

[hagedl]

Built our new home with 11K gallon plaster SWG Pool and Spa 2013 in Cape Coral, Florida. We did not move here until 2 months ago and had a moderate amount of brown calcium scale in spa and pool. Discovered that the landscaper had installed irrigation water sprinklers in the back garden which sprayed high phosphates from the community reclaimed irrigation water into the pool for the past year. I capped the sprayers and stopped that problem. Next we found that every time we used the spa we became ill with crusty eyes, congestion, headaches - SWG was wired to spa so every time we heated it we were being bathed in very high toxic levels of chlorine. That problem has been corrected and we can turn off the SWG before we heat the spa so Chlorine levels are now 2 - 3. Pool guy never kept pH low (which I can see would be impossible with only weekly visits) Chlorine was always over 5, pH impossible to maintain below 8.2 even with TA 80, CH 400 ppm, Stabilizer 60, TDS 4200, Salt 3000. In past 2 months I have added a quart of Jack's Magic Magenta(about 2 months ago), last week added 64 oz Scaletec Plus. Sequestrate Level 12. Have also added Salinity Phosphate remover periodically with phosphates 2500 initially. Washed filter every few days with lots of milky calcium water being released. Brushing all surfaces twice a day for 2 months as advised by pool builder. Scale is 90% gone but still difficult to maintain pH below 7.4 and he advised keeping it less than 7 to remove the scale. Have been trying to maintain pH about 7.2 and check twice a day in order to remove scale. I would like to add borates to help stabilize the pH rate of rise. Should I wait until scale is completely gone? Or will adding now actually help me to keep the pH down and aid in removal/reacurrance of remaining scale.

 

[JasonLion]

Welcome to TFP!

Phosphates are not really an issue, and certainly have nothing to do with anything else you have mentioned. My phosphate level has been over 4,000 without causing any problems at all.

If you let the TA go down to around 60 you will have less trouble with the PH constantly going up. If you lower TA and add borates, you can lower TA even further (down to 50) which will help even more.

CH is a bit high, though not seriously. Presumably it was higher before the scaling started. I'm concerned with where the CH is coming from. Have you tested your fill water CH level? It is uncommon to have calcium scaling in Florida.

While you are working on all of that, you should do some reading in Pool School, see the link near the top right of every page.

 

[hagedl]

Our SWG was wired so that every time we used the spa and raised the temperature the system would "think" that the pool temp was higher and put out enough Chlorine directly into the spa and on us to chlorinate the whole pool. That has been fixed and SWG is turned off when we heat the spa. I thought the scale was calcium phosphate and does improve when I add phosphate remover - but I am also scrubbing and trying to keep pH low to get rid of scale.

Am wondering if I add borates now if it would be helpful or if it would prevent me from achieving a pH of 7.2 while I am trying to remove the scale.[/B] Love this site and have read about everything here!! As a new pool owner I so appreciate Pool School.

My fill water was Cape Coral City water - same as all my neighbors and they do not have this problem. Could it be due to the plaster in my pool being defective? The clouds of white when I sweep the pool have greatly diminished and water when I hose the filter much less milky.

 

[JasonLion]

Borates change thing so you need to use more acid to make the same PH change. It is still possible to lower PH, it just takes more acid. In situations where the PH is constantly going up, adding borates (and not doing anything else) means you can go longer between times you need to lower the PH, but you will need more acid each time, averaging out to using the same total amount of acid with or without borates. Adding borates also means you can lower the TA a bit further, which does reduce the total amount of acid you need to use.

Having a high phosphate level does mean that you will get calcium phosphate scale instead of plain calcium scale. But it doesn't make any noticeable difference in getting scaling or not getting scaling.

Simply lowering the PH to 7.2 isn't going to remove any noticeable amount of calcium scale.

You should measure the CH level of your fill water. The calcium must have come from somewhere. You need to figure out where the CH was coming from, or you are going to have a tough time preventing this from happening again in the future.

It is critical to keep the PH at 8.0 or lower. It is always possible to do so, simply add more acid more frequently.

 

[hagedl]

I have drained and refilled enough pool water to lower my CH from 600 to 330-390 depending on which pool store I choose to believe on a given day. My reading was 800 - now 490 using Leslie's Complete Poolcare DPD Test Kit. Calcium scale has markedly improved so at least I know CH is going down. With all my scrubbing past 2 months it just kept redepositing. High CH was from the irrigation sprinkler system spraying into the pool for a year - now corrected. City water is very low. Have maintained pH 7.2-7.4 consistently.

I have taken the SAME water sample to Leslie's and Pinch-A-Penney at the SAME time on 3 separate occasions and they differ from my own testing and from each other significantly especially with salt and CYA levels. I think I should believe the salt level from my Nano SWG. Is there a really reliable test out there for CYA especially? I have added the borates as I am very sensitive to chlorine so am aiming for FC = 2, CYA = 40. I get a level of 35 with my Leslie's kit. Leslie's tells me CYA = 25 and SW Pools tells me it is 50. My phosphates are 1000 - 2500 depending on who you believe and they INSIST that I treat - which I will not do since attending Pool School. They all also insist that I increase my CYA to 60-80. Am I MUCH at risk for algae if I don't considering my borate level of 50? Please advise. Thanks a bunch.

 

[JasonLion]

With CYA around 30, you are using up the SWG cell lifetime at roughly twice the rate that you would with the recommended CYA level of 70-80, and generally lowering the stability of your pool chemistry (more PH increase, slightly higher odds of getting algae).

It is extremely common for pool store water testing to be wildly wrong and inconsistent from visit to visit. You should trust your own testing, rather than depending on pool stores.

I agree that you should ignore the phosphates.

The Taylor CYA test where you add liquid to a view tube until the black dot disappears is the best available CYA test.

With CYA at 40 and FC of 2 you are just within our recommended FC level when using a SWG with that CYA level. In general it is safer to have a little more margin than that, but nominally you should be alright. The main issue is wearing out the SWG much more quickly than normal, and the increased PH drift.

"very sensitive to chlorine" might be any of a wide variety of issues. Regardless, 99% of the people who believe they are sensitive to chlorine are actually sensitive to chlorine disinfection byproducts. Keeping the FC level comparatively low is going to increase the levels of disinfection byproducts, not reduce them.