Calcium Flakes in a new pool

[RobMM]

Hi. I'm a new user that could use some help. I have a new pool completed just about 1 year ago. (In ground, plaster, Jandy Tru Clear SWG) We did all of startup brushing and filter cleaning steps. Within 3 months of originally doing the startup, we were getting tons of calcium flakes. The Jandy rep came out and changed some setting on the SWG so that it self cleaned more frequently with the filter running 8 hours/day. That help a slight bit, but we were still getting significant flakes. Calcium hardness readings were over 1000 and I replaced 1/4 of the water 3 months after filling. That didn't changed the CH much. We lived with the problem and vacuumed the pool every few days and cleaned the filter frequently to get rid of the flakes. There were less flakes over the winter with the SWG turned way down to 30% and the filter only running 6 hours/day. However, anytime we used the heater, we were swimming in a snow globe of flakes. I'm ready to tackle this problem! My new pool guy has suggested draining most of the water and basically starting over, which seems to be the only real way to lower the CH. He also suggested that this particular SWG (Jandy Tru Clear) raises CH more than most SWG and he only sees problems at other pools with that brand. I've ordered the TFP test kit, am now on Pool Math, and am ready to geek out on water chemistry to solve this issue! Thanks for any advise.

Current readings until new test kit arrives:
PH: 7.6
Total Alkalinity: 120
Calcium Hardness: 1000
Total Chlorine: 4
Free Chlorine: 4
Salt: 2650
Water Temp: 72
I also tested out Calcium Hardness from our water supply: 300

 

[Rancho Cost-a-Lotta]

Hey Rob,

We won't give much consideration to the test results, but if they are close, you will have some challenges to deal with. A CH level of 1000 is simply unmanageable. If your fill water is really at 300, you'll experience a constant rise in CH levels that will require a water exchange every couple years. Draining a little won't do much with high CH fill water.

Do you have a whole-house water softener? If so, using softened water for evaporative top-offs will help to reduce or eliminate CH rise. I use an RV softener (link in my sig) that takes my fill water from CH 125 to less than 10.

Good move on ordering the test kit. When you receive it, take your time performing the tests. Post a full set of test results and include the TA and Ch of you fill water. In the meantime, read up on ABCs of Water Chemistry, Calcium Scaling, and Calcium Saturation Index (CSI) in Pool School. Key to reducing scale is maintaining a slightly negative CSI (-0.30 to 0.0).

Lose the pool guy...you won't need him anymore.

 

[Cena_sea]

I agree 1000 CH and a 300 CH fill water sounds really high. The problem with a high fill water CH is that when water evaporates I read on here the CH doesn't--so you add new water but the calcium from the old water is still there. I think your other numbers look good.

I haven't heard of a SWG adding any calcium to the pool. My SWG has not increased the CH numbers for me (if anything they are dropping gradually due to a low CH fill). Have you tried just using liquid chlorine (not pucks or powder) as I believe liquid chlorine does not add CH.

Edit: Okay I searched and there is a thing about SWG and white flakes. I'd never heard of that. I didn't realize the SWG needed to be cleaned too. There's another thread on reverse osmosis that might help you too.

Is high chlorine (15+ PPM) a health concern? I have high CYA (160ish) + Drought in California

Hey all, We bought a new home last year with a pool and the CYA is testing really high. Pool Store said it was about 200+ and a dilution test seems to put it at 160ish. I've switched to liquid chlorine and ditched the pool store. But we are on a well (which is all sorts of issues on its own...

www.troublefreepool.com

 

[JoyfulNoise]

Your TA and CH are way too high for a pool in the desert southwest. With those numbers, your SWG is always going to be a snowflake generator.

Once you get your test kit and better numbers, your goals are going to be -

1. Reducing CH by whatever means necessary even if that means draining and starting over;
2. Getting the TA reduced to 60ppm or even less;
3. Targeting a tight pH range of 7.6-7.8
4. Coming up with a way of conditioning your fill water to remove calcium (water softener).

If you can do all that, your SWG will stop spotting snowflakes.

 

[kul]

I’m surprised by your 300 CH fill water reading. I also live in LA (LADWP) and mine is 100. I agree with the above post about considering a water softener to do your top offs.

 

[RobMM]

Thanks for all of the advice! This group has been very insightful. I've read lots of great info and am also on the Pool Math app. I received the new test kit and got the following readings:
FC: 4.6
PH: 7.
TA: 180
CH: 1000
CYA: 80
SALT: 2650
CSI: .78

I'm draining the pool today and starting fresh to hopefully resolve the Calcium issue. I will clean the filter and the Jandy salt cell before refilling. I retested our fill water and got a Calcuim reading closer to 200, so that seems to put me in a better position. I'll starting with adding liquid chlorine and slowly add the salt in to bring it back to the proper salt level. Any other tips or things I should know regarding starting back up with fresh water? Also, my pool guy used to occasionally add "conditioner". Is that recommended?

 

[JoyfulNoise]

Consider installing a water softener and using that to fill the pool. With a CH of 200ppm and high evaporation rates, your pool water CH is going to climb up quickly.

 

[ajw22]

Once you refill the pool you will need to lower your TA.

TA - Further Reading

www.troublefreepool.com

Why Should TA be Lowered with a SWG?​

Usually a TA on the high end is fine if the pH is stable. However TA does need to be adjusted down with an SWG. The problem is, INSIDE the cell, the CSI is very different than in bulk pool water.

With high TA and aeration from the bubbles the SWG creates, you'll get faster pH rise inside the cell and so there's more potential for scaling. With current reversal, the cell tends to stay clean but you'll get more snowflakes out of the returns. Calcium hardness is only one part of the equation.

If the SWG cell pH rises much above 10 (and it can easily do that) and if there is sufficient levels of carbonate ions available (CO3--), then you will get calcium carbonate precipitation. The higher the TA and pH, the more carbonate anions are available.

Borates are particularly helpful preventing scale in a SWG because the pKa for boric acid / borate anion buffering is approximately 9. That essentially means you get the maximum buffering capacity at a pH of 9 and that tends to hold down the pH rise inside the cell. Keeping the pH below 10 in the SWG cell reduces the risk of calcium and magnesium scaling (insoluble magnesium hydroxide precipitates at a pH of 10.2 or so).

 

[MITBeta]

Also, my pool guy used to occasionally add "conditioner". Is that recommended?

Yes. That's the CYA in the test you ran with your new kit. Add 30-40ppm to start. Best way is with granular Cyanuric acid via the sock method. Fill an old sock with the powder and find a way to hang it in front a return. Don't let it touch the side or bottom of the pool. Squeeze every few hours.

 

[RobMM]

Just drained (completely) and refilled my pool. Below are my number before adding anything. I've gone to "Pool School" (super helpful) and know the target numbers I'm aiming for. Any advise on which to start with first? My pool guy said I need to first add ScaleTec to neutralize the minerals/metals in the water, then get the PH correct before adding any Chlorine. I'm assuming I'll add liquid Chlorine while bring the salt up (slowly) before turning on the SWG. Any other advise or re-directs? I can't find any info on needing to add the SCALETEC. Thanks for your help!
FC: .5
CC: 1
PH: 8
TA: 90
CH: 150-250 (I used 2 different tests 2x each and got different results.
CYO: 0
Acid demand = 1 drop

 

[Rancho Cost-a-Lotta]

Looks like you're on the right track. Use liquid chlorine to keep FC above 5 ppm until the SWG is running.

You can add salt in stages any time.

Add CYA in stages until you reach your target of 60-80 ppm. 70 ppm works pretty good for me.

Trust your Taylor-based calcium test. We rarely see CH 250 results for fill water in our area. That's Colorado River water levels.

Can't help with the Scaletec or sequestrant. I don't believe my PB added any after my build.

Here's a BUMP for the sequestrant question.

 

[mknauss]

I do not believe Los Angeles water has significant Iron in it. Do you have red staining in your toilet bowls, sinks, etc? If not, no need for any sequestrant.

 

[RobMM]

Thanks for the great info! So if my CH with the new water is only 150, then do I need to add Calcium? How soon should that be added to avoid any plaster issues? I don't want to ruin the plaster, but my Calcium got so high previously (over 1000) that I'm skeptical to add any more.

 

[mknauss]

If your pool is normally uncovered, keep the pH and TA at the upper levels. Then your lower CH will not matter. It will rise with evaporation.