Calcium Buildup

[vegas-doug]

Hello,

I am having some calcium buildup on my salt cell (45 to 60 days between cleaning), much more than I feel I should be having. Previous years I ran a Pentair IC60 and injected 50% acid/50% water via a stenner pump a few feet before the salt cell to keep ph stable with minimal effort. While this seemed to keep the salt cell clean I think it shortened the life of 2 cells to two summers each so I replumbed this last spring to inject AFTER the cell and put in a generic ($600) cheaper salt cell from discount salt pool but I have been having more problems with calcium.

My numbers are the following:
FC 0.35
ph 7.4
TA 79
Calcium 482
Cyanuric 53
Salt 3117
Pool temp 78-86 degrees

CSI is -0.2 per pool math. I should also note that I added an entire 64 oz bottle of Beautec Easycare Cale Preventative a month or two ago.

Any thoughts or ideas why I'm having such trouble.

 

[Texas Splash]

Doug, my first concern are the test numbers. Unless you have a unique test kit, they appear to be from a pool store because those aren't numbers provided by a TF-Series test kit or Taylor K-2006C. It's very difficult to diagnose the water with those numbers. As such, it's very possible one or more of them are incorrect and misleading you. Do you have a TF-Series kit or Taylor K-2006C?

 

[vegas-doug]

Doug, my first concern are the test numbers. Unless you have a unique test kit, they appear to be from a pool store because those aren't numbers provided by a TF-Series test kit or Taylor K-2006C. It's very difficult to diagnose the water with those numbers. As such, it's very possible one or more of them are incorrect and misleading you. Do you have a TF-Series kit or Taylor K-2006C?

I weekly test ph and TA with taylor and monthly do a more comprehensive testing at pool store and with the taylor test kit so I am 100% confident the numbers are reasonably close to those listed. For example taylor kit had 7.4-7.5 ph and 70-80 TA which matches pool store results. FC only test using strips unless I need a more accurate measurement. Salt cell salinity was reading within 70 ppm as well.

I have always had to add a small amount of baking soda (guessing around 1/2 cup weekly) to raise TA. If I didn't TA would drop to 60 or below. I usually shoot to keep the TA at 70-80 even though pool store recommends 100. pH is always stable between 7.4 and 7.6 during summer as I use the stenner to inject small amount of acid every morning.

 

[proavia]

Forget about the pool store results and test strips.
To successfully manage your pool, you need accurate results - every time.

Post a full set of current test results from your Taylor test kit.
Which exact Taylor kit do you have?
Do you have and use a Speedstir?

FC
CC
pH
TA
CH
CYA
Water temperature
Salt (from a Taylor K-1766)

Letting your TA sit at 50-60 is totally fine. And chances are you will be able to let the pH sit in the 7.6 to 7.8 range while maintaining a slightly negative CSI (given the reported CH).

If those PS numbers are anywhere near accurate, you are running your FC way to low.
FC/CYA Levels

 

[vegas-doug]

Forget about the pool store results and test strips.
To successfully manage your pool, you need accurate results - every time.

Post a full set of current test results from your Taylor test kit.
Which exact Taylor kit do you have?
Do you have and use a Speedstir?

FC
CC
pH
TA
CH
CYA
Water temperature
Salt (from a Taylor K-1766)

Letting your TA sit at 50-60 is totally fine. And chances are you will be able to let the pH sit in the 7.6 to 7.8 range while maintaining a slightly negative CSI (given the reported CH).

If those PS numbers are anywhere near accurate, you are running your FC way to low.
FC/CYA Levels

FC is only low because the salt cell is no longer running due to calcium buildup. I typically run cell to keep within the recommended levels. Test strips are fast and provide a way to see rough amount of chlorine in the pool, besides FC and CC have no bearing on CSI, at least based on the pool math calculator.

I do not have a speedstir but I have the K-2006 kit. Two days ago I tested pH and it was 7.4, TA was 70. CYA was 50 when tested 3 weeks ago and pool has not been drained or really used much since then. CH is never very low as I live in Las Vegas with very hard water but even at 650 CH my CSI would still be negative. Late winter I drain about 25% of water to reduce calcium level but I will check with my taylor kit when I get home. Water temp has been between 78-86 degrees the past month (morning vs afternoon). Though the last 2 days the pool has cooled slightly to 76 degrees this morning. Salt level as dialed in months ago after draining using both a Taylor salt kit, new salt cell reading, and pool store results so there is absolutely no doubt it is over 3,000 but can check that again as well.

Is there any danger in running TA at say 50 long term for pebble pool as long as I keep tabs on the CSI?

 

[Texas Splash]

Is there any danger in running TA at say 50 long term for pebble pool as long as I keep tabs on the CSI?

No problem.

Doug, good to know you have the K-2006 and were able tp provide some of those numbers. I plugged some numbers into Poolmath and came up with roughly the same (slightly negative) CSI as you did in post #1. That said, your cell "shouldn't" scale-up so quickly. However I will add that even if I keep my water slightly negative, I seem to find some scale as well. Chemistry and turbidity within the cell itself (aeration & pH) may have something to do with that. As long as you are utilizing and relying upon your K-2006 test kit for valid results, your chemistry should be as good as it can be.

While it is true that the FC and CYA aren't the main reason for your thread here, I do want to remind you to refer to the FC/CYA Levels for what TFP considers ideal daily ranges and the minimum amount of FC to prevent algae. If you still have some powder & drops from the FAS-DPD portion of your K-2006 kit, we encourage you to use that versus the strips. If you're in a hurry, use the OTO drop-tester for a quick snapshot of FC & CC (Total Chlorine).

 

[mknauss]

Unless you can get soft water for your make up water, you likely need to use borates to reduce the pH rise in your SWCG to reduce calcium formation. I luckily have never had to clean my SWCG cells. Even before I used soft water for make up water, I could have 800 CH and keep the cell clean. I did not use borates. So I also suspect your pH or TA are not being tested accurately. Might want to check the reagents used, process, etc.

 

[vegas-doug]

Unless you can get soft water for your make up water, you likely need to use borates to reduce the pH rise in your SWCG to reduce calcium formation. I luckily have never had to clean my SWCG cells. Even before I used soft water for make up water, I could have 800 CH and keep the cell clean. I did not use borates. So I also suspect your pH or TA are not being tested accurately. Might want to check the reagents used, process, etc.

No soft water is available to the auto-fill. Plumber plumbed it in to the irrigation line rather than the hose bibb so it is bypassing the house completely. Though the hose bibb doesn't have soft water either.

I will check the reagents to ensure they are still good. I checked my testing method against the video instructions Taylor has on youtube (

). I am testing exactly as they are so that is not the problem.

I will look into borates as I know absolutely nothing about them.

 

[mknauss]

If you have soft water, I would look at what it would take to get a soft water line to the pool pad.

Borates in pool - Further Reading

www.troublefreepool.com

 

[vegas-doug]

I checked the regents and a few of them are expired in May 2023, while a couple were expired summer 2022. So, I ordered a new test kit to re-check the levels and see where I'm at. Hopefully can figure something out.

 

[proavia]

I agree with Marty that it would be best to figure out a way to plumb soft water to the autofill.

Usually running a 1/2" or 3/4" PVC line from the softener location (garage?) along the side of the house toautofill works. My neighbor ran a PEX water line from the softener thru the attic crawl space and converted to PVC where it exited the soffit to then connect to the autofill. Another way is to tap into a cold water line in a bath or kitchen that is on an outside wall near the autofill location. In any of these options, it's important to include a backflow prevention device in the line.

 

[vegas-doug]

I tested with the new Taylor Test kit and it essentially confirmed the previous results (with expired Regent) on the same water. So I have no doubt that my CSI is negative. But still have no idea why I would be getting scaling on the salt cell so much. Going to look into how I can tap into my soft water.

I do use potassium pellets instead of salt. Any potential issues with the pebbletec pool?

 

[proavia]

I do use potassium pellets instead of salt. Any potential issues with the pebbletec pool?

Any particular reason you use potassium chloride instead of sodium chlorine?
Potassium chloride gets spendy really quick.

Let's see what @JoyfulNoise has to say about the use of potassium chloride for softening water used in a pool.