Near instant SWG Calcium buildup, advice?

[chicotunner07]

Hi Everyone,

Semi-pool noob here, my SWG pool turned 1year old last week. I learned a lot this past year, and have made some great changes that have helped tremendously, mostly found on this forum!

Anyways, my reason for this post, is calcium buildup on my SWG. I cleaned my SWG a total of about 7 times these past 12 months, every single time using diluted Muriatic acid (5to1 water/acid) as recommended by the manufacturer. I have tried to wrap my head around why my SWG collects so much dang calcium deposits.

I cleaned my SWG 2 days ago, and there is already a thin white film covering the fins, is this normal? I know cleaning with diluted acid will eat away at the precious minerals on the plates of the SWG, but there is no way to manually clean it with wooden sticks/popsicle sticks/paint stirs as ive seened mentioned here, the white calcium chunks are incredibly hard, ive succesfully knocked off some large chunks with a metal screw driver (completely avoiding the plates of course) but there is no way the center of the plates are getting cleaned without the acid.

Here are my pool deets and my most recent test using a TF-Pro Salt Test

10,000 gal Gunite/Concrete pool
Located in Central-ish Florida, Port St Lucie to be exact
Uncovered, almost no shade/ no trees
Hayward TurboCell S3 Salt Cell TCELLS325

Most recent test results
FC-7
CC-0
PH-7.5
TA-60
CH-500
CYA-50
SALT-3100
Temp-82*
CSI- (-0.300)

Any insights or recommendations would be extremely helpful!

thank you!

 

[ttroglio]

How much calcium we talking? Post pics? What you describe is normal operation. Electrolysis in the SWG takes the NaCl (salt) and breaks out the Cl and sends it into the water. The leftover Na (calcium) is left on the plates.

Your numbers look OK to me. I clean my SWG about every 3-4 months and there is not a huge buildup.

 

[mknauss]

With a consistent CSI of -0.3, you should never get any scale build up on the SWCG.
It is not 'normal' to get scale in a SWCG.
Using acid that much to clean the cell, your SWCG will have a much shortened life.

You could try borates to reduce the pH rise in your cell.

Borates in pool - Further Reading

www.troublefreepool.com

 

[PoolStored]

I have a few thoughts for you. While I agree with Marty, you should never get scale, and borates may be your best option...you might try a few things.

1. Can you confirm that your cell is in fact reversing polarity...if not, that may be the source of the problem. Reversing polarity is intended to flake off any mineral deposits. (my *guess* is this is your problem).
2. It would be fairly easy to reduce the CH in the water with a water exchange to reduce your CH. While 500 is *particularly* high, reducing it may eliminate the buildup.
3. The CSI in the pool is going to be more negative than in the cell because of the OH- production. A more negative CSI becomes corrosive <-.3, but typically takes a period of time. If you want a short term test, reduce your CSI another .1 and see if it goes away. Reducing your pH to 7.4 or 7.3 for a short period of time is the best way to test. If that works, I think #2 above is your best option.

Net Net, confirm your cell is reversing polarity, then either reduce CH or try borates.

ONE NOTE: Borates, when added, will reduce pH and buffer it. If I add 50ppm Borates to my pool when pH is 7.6, the borates reduce my pH to 7.4...at it SITS there...(I haven't added any MA this year and my pH has been 7.4 all year). Use the "effects of adding" before you add borates to figure out how much borates will reduce pH...and make sure that the ending pH is a pH that you want and will be good for your end state CSI.

 

[chicotunner07]

How much calcium we talking? Post pics? What you describe is normal operation. Electrolysis in the SWG takes the NaCl (salt) and breaks out the Cl and sends it into the water. The leftover Na (calcium) is left on the plates.

Your numbers look OK to me. I clean my SWG about every 3-4 months and there is not a huge buildup.

Sorry, no picture of the buildup, ill grab one next time i clean it, but its significant i would say.

I found this picture online, mine wasnt this bad, but it was getting there, it took the diluted acid almost 15-20 minutes to disolve all of the buildup.

 

[chicotunner07]

I have a few thoughts for you. While I agree with Marty, you should never get scale, and borates may be your best option...you might try a few things.

1. Can you confirm that your cell is in fact reversing polarity...if not, that may be the source of the problem. Reversing polarity is intended to flake off any mineral deposits. (my *guess* is this is your problem).
2. It would be fairly easy to reduce the CH in the water with a water exchange to reduce your CH. While 500 is *particularly* high, reducing it may eliminate the buildup.
3. The CSI in the pool is going to be more negative than in the cell because of the OH- production. A more negative CSI becomes corrosive <-.3, but typically takes a period of time. If you want a short term test, reduce your CSI another .1 and see if it goes away. Reducing your pH to 7.4 or 7.3 for a short period of time is the best way to test. If that works, I think #2 above is your best option.

Hey, thanks for the input

1) while i cant be 100% sure, i have seen the display on the control unit switch between Pol1 and Pol2, and from what i read in the manual, it automatically switches polarity on its own. But i will look further into this.
2) I did also think the CH might be too high, but hadnt seen anyone mention this as a source, i will look into the process of reducing it, from what ive read online, water replacement is the only solution, might take a while to get it done.
3) I'll test the 7.4-7.3 PH reduction and report back! Thanks

 

[chicotunner07]

With a consistent CSI of -0.3, you should never get any scale build up on the SWCG.
It is not 'normal' to get scale in a SWCG.
Using acid that much to clean the cell, your SWCG will have a much shortened life.

You could try borates to reduce the pH rise in your cell.

Borates in pool - Further Reading

www.troublefreepool.com

Thanks for the input, i have read a little on borates, but wanted to ask for advice before adding another chemical and cost to my list! But its definitely on my radar!

 

[PoolStored]

Electrolysis in the SWG takes the NaCl (salt) and breaks out the Cl and sends it into the water. The leftover Na (calcium) is left on the plates.

This is not true. Na is SODIUM, not calcium.

Salt is sodium(NA) and chloride(CL). The Na and Cl break apart as soon as salt dissolves in pool water. The chloride ions lose an electron at the cell plate to form chlorine gas Cl2.

Electrolysis is the process of removing an electron from the chloride and putting an electron on the hydrogen ions that make contact with the opposite side of the cell plates.

So, basically, a chloride ion is on one side of the plate and a hydrogen ion is on the other side of the plate and an electron moves from the chloride ion through the plate and onto the hydrogen ion.

The electrolytic cell generates chlorine gas at the anode and hydrogen gas at the cathode. The chlorine gas rapidly dissolves into the water and hydrates to form a mixture of HOCl/OCl- that is pH dependent and the hydrogen gas bubbles out of the return (hydrogen is not soluble in water).

 

[PoolStored]

2) I did also think the CH might be too high, but hadnt seen anyone mention this as a source, i will look into the process of reducing it, from what ive read online, water replacement is the only solution, might take a while to get it done.

What is the CH of your fill water?

See "no drain water exchange" here:

Draining - Further Reading

www.troublefreepool.com

 

[PoolStored]

while i cant be 100% sure, i have seen the display on the control unit switch between Pol1 and Pol2, and from what i read in the manual, it automatically switches polarity on its own. But i will look further into this.

It does do it automatically. There may be an issue with the main board or the cell that is not allowing it to reverse polarity.

See "Troubleshooting the Main Board" and the note on the polarity reversal here:

Hayward Aquarite SWG - Further Reading

www.troublefreepool.com

 

[chicotunner07]

What is the CH of your fill water?

See "no drain water exchange" here:

Draining - Further Reading

www.troublefreepool.com

Not sure what the CH of my fill water is, silly question, but would i test it the same as i would my pool water?

 

[PoolStored]

Not sure what the CH of my fill water is, silly question, but would i test it the same as i would my pool water?

The only way to reduce CYA or CH is to replace water. When you have evaporation, and you replace water, CYA and CH stays in the water (increasing CH concentration). When your fill water has high CH, your CH will climb faster than someone that has lower CH input water.

BTW, you only need to test it once, so you know if your input water has high CH or not. I created another pool in pool math and input my source water pH, CH and TA.

 

[chicotunner07]

The only way to reduce CYA or CH is to replace water. When you have splash-out, or evaporation, and you replace water, CYA and CH stays in the water (increasing CH concentration). When your fill water has high CH, your CH will climb faster than someone that has lower CH input water.

BTW, you only need to test it once, so you know if your input water has high CH or not. I created another pool in pool math and input my source water pH, CH and TA.

Thank you for your help!

I'll be checking my tap's CH tomorrow.

 

[PoolStored]

CH makes a big difference if you have a vinyl, plaster or FG pool. In port St. Lucie, I'm assuming plaster. If you fill out your signature, it would help...

Create Your Signature - Further Reading

www.troublefreepool.com

 

[Bperry]

Thank you for your help!

I'll be checking my tap's CH tomorrow.

To help confirm, the SWCG should not cake up like that. Either something is wrong with it or something is wrong with the test results. I’ve gone two full seasons and never had a need to clean the cell. Do you have scaling anywhere else around the pool?

 

[ttroglio]

This is not true. Na is SODIUM, not calcium.

Salt is sodium(NA) and chloride(CL). The Na and Cl break apart as soon as salt dissolves in pool water. The chloride ions lose an electron at the cell plate to form chlorine gas Cl2.

Electrolysis is the process of removing an electron from the chloride and putting an electron on the hydrogen ions that make contact with the opposite side of the cell plates.

So, basically, a chloride ion is on one side of the plate and a hydrogen ion is on the other side of the plate and an electron moves from the chloride ion through the plate and onto the hydrogen ion.

The electrolytic cell generates chlorine gas at the anode and hydrogen gas at the cathode. The chlorine gas rapidly dissolves into the water and hydrates to form a mixture of HOCl/OCl- that is pH dependent and the hydrogen gas bubbles out of the return (hydrogen is not soluble in water).

lol. yes. Sodium. Its been many years since the periodic table and I were friendly.

 

[mgtfp]

lol. yes. Sodium. Its been many years since the periodic table and I were friendly.

 

[SoDel]

I’ve run my SWG for 4 seasons and while I do check it when the automation tells me to, I have never had any need to clean it. I’m wondering a bit about your pH of 7.5 in combo with your other numbers. I also keep TA in the 50 to 60 range but with my pool, it’s not possible to maintain a pH as low as 7.5 for more than a day or so unless acid is added (I don’t have any type of cover on it during the swim season). Was the 7.5 like your nominal target and it rose from there or how are you managing pH? The pH has the most effect on CSI so if it wandered high for a while between acid additions with CH that high, it might explain the unusual degree of scaling in the SWG.

FWIW, the way I make dealing with pH easy for me is keep CH low enough (250) so pH close to 8 still results in slightly negative CSI. TA of 50 to 60 will tend to stop pH rise at around 8 and slow it a lot as it approaches 8. If your fill water isn’t high CH, it may make sense to reduce your pool water CH (by water replacement) so you don’t need such a tight leash on pH to keep CSI slightly negative. I target pH 8 with TA of 50 or 60 so I don’t need to add acid — if it rises above 8, I know TA is still a skosh too high. You might want to revise your pH target to, say, 7.8, and balance the rest of the water chemistry so CSI is still negative at this target. This way if (when) it drifts slightly above target between acid additions, you’re still ok.

 

[chicotunner07]

The only way to reduce CYA or CH is to replace water. When you have evaporation, and you replace water, CYA and CH stays in the water (increasing CH concentration). When your fill water has high CH, your CH will climb faster than someone that has lower CH input water.

BTW, you only need to test it once, so you know if your input water has high CH or not. I created another pool in pool math and input my source water pH, CH and TA.

So i tested my home water source at the hose, it read 75 CH. Is this considered high?

 

[chicotunner07]

CH makes a big difference if you have a vinyl, plaster or FG pool. In port St. Lucie, I'm assuming plaster. If you fill out your signature, it would help...

Create Your Signature - Further Reading

www.troublefreepool.com

Sorry, i put all of the details on the first post, ill add them to my sig.

Yes, pool is gunite/concrete which is considered plaster right?