Calcium Hardness Balance

Water Chemistry
1

I have been having an issue with getting my calcium.jardness to increase and maintain at a level of 200. I thought it was my reagents for LaMotte ColorQ, but that didn’t quite do it. I have the following readings:

FCL 1.74; TCL 1.97; CCL .23; pH 7.3; Alk 97; CH 163; CYA 53

I have added nearly 15 lbs of Calcium Hardness Increaser and the highest I got in CH reading was 185 and now it is back to 165.

I thought I had a leak last year, but nothing noticeable in dye or bucket tests. What can be the issue?

I have a kidney bean ungrounded vinyl pool aboit 15,000 gallons with a DE filter and automatic chlorinator.

2

We’d glad to assist you. What was the calcium reading before you added the 15 pounds of calcium hardness? Are you dissolving the calcium into a bucket of water before adding it to the pool?

1 Like
3

I am sorry I never got notification that you responded. I think I posted the following but not under my account:

Hello!

I cannot figure out if I have a chemical or plumbing problem or something else.

~16,500 gal Kidney Bean Vinyl Pool with new Hayward Pro Series S244T Sand Filter residing in the northeast using a Hayward CL200 In-line chlorinator with 3 in. Stabilized Chlorine Tablets Tri-Chlor.

I am always chasing my Calcium Hardness levels up and my CCL levels down. I was told that CH should not be fluctuating so much - unless you have leak.

I refill water about 3-4 in. every week. However, when its time to open pool, the water is filled to the top, which makes me think if there is a leak, it would be in the plumbing. In the past several years, the return and skimmer plumbing were redone, which leaves the main drain. I hear the only solution is to plug it and not use it, but since the water is retained in the pool throughout the winter, then maybe the “break” in the pipe is above water level (my pool equipment is about 8-10 ft higher than pool).

Before I assume a leak in main drain and plug, I want to see if there is something chemically wrong.

I keep a Google Sheet of my pool chemical readings. The last three readouts from LaMotte ColorQ Pro 7 2056 and what I did:

5/22/22: FCL 5.29,  TCL 6.60, CCL 1.3, pH 7.4, Alk 68, CH 126, CYA 66 - set chlorinator to 4, added 10lbs Calcium Hardness Increaser

5/27/22: FCL 2.46,  TCL 3.79, CCL 1.3, pH 7.5, Alk 88, CH 141, CYA 54 - Added 5 chlorine tablets; 10lbs Calcium Hardness Increaser; 3in water

5/28/22: FCL 2.20,  TCL 2.50, CCL 0.3, pH 7.5, Alk 78, CH 182, CYA 50 - Added 4lbs of Baking Soda

6/03/22: FCL 1.52,  TCL 3.67, CCL 2.2, pH 7.6, Alk 96, CH 150, CYA 54 - Added 4 chlorine tablets

I added 3 in. water at least one other time during this period including it raining, but I am lost cause its like this all season long. I spend so much money on CH Increaser and liquid pool shock (Sodium Hypochlorite 10-14%). My next step might be to add 2 gal of liquid shock and see where that gets me…thoughts?

4

Hello,

I’m a little confused. In your first post you listed a sand filter. In your last post you list a DE filter. Which do you have?

The only things that cause a loss of calcium are water loss other than evaporation, like splashing water out of the pool or a leak or a gunnite/concrete pool or stone accessories such as a waterfall that could leach calcium from the water. Since your pool is vinyl it can’t affect the calcium level. If you don’t have any stone and mortar accessories that eliminates that source.

I’m assuming your plumbing is plastic. So that eliminates that source. Even a water leak of 3" every week or so  (and that sounds high) shouldn’t affect the calcium level that much. And more to the point, why do you want a CH level of 200ppm? 200 ppm is way more than you need for a vinyl lined pool. And it isn’t high enough for a plaster/gunnite pool. Since you don’t have to worry about pitting of a plaster/gunnite/marcite/ fiberglass pool surface you only need enough calcium, along with PH and TA to prevent scaling on the vinyl surfaces and plumbing lines. This is determined by the Calcium Saturation Index(CSI). That number needs to be below 0.6

Your CSI, based on the last numbers given is -0.7. While this is outside the ideal range of 0.6 - -0.6, it can easily be brought within that range by increasing the PH OR TA.

Maybe the ColorQ photometer needs to be calibrated (if it can be). You could always find a pool store and take a water sample and have them check the CH levels.

Your bigger concern is you don’t have any free chlorine in the water. The CC is above the FC levels. This means that none of the chlorine you are putting in the water is available to sanitize the water. In this case, if the water is clear, it’s because your aren’t putting enough chlorine in the water for the CYA level. Higher CYA levels require more chlorine to sanitize the water. Your last CYA level was 53. For that CYA level, the bare MINIMUM for FC, without any CC is 4ppm. The ideal range is 6-8ppm.

And because the CC level is above .5 - 1.0ppm you likely have organics in the water that need to be killed or you will eventually get an algae bloom.

And keep in mind that every Trichlor tablet adds more CYA to the water. 3" Trichlor tabs weigh about 8 oz. and that adds about 2.2 ppm of CYA to the water.

Let us know if you have any questions.

j

1 Like
5

Hi J,

First, thank you for responding (still got no notification - need to check settings).

I should have been more explicit, but my sand filter is NEW. I did have a DE Filter.

My pool is vinyl, but the patio is pavers and there is a wall of stone with a waterfall. However, I do not use the waterfall as it needs to be replaced.

The plumbing shuld be PVC at this point (though I cannot be for certain for the main drain). It seems the piping was originally done with flex PVC. I was aiming for a 200 CH level due to the constant reduction in CH readings I was getting. I must have read somwhere that 100-200 is acceptable for vinyl. I guesss the good thing is that it is not a huuge concern, but still dont understand the significant CH loss. I checked out the Pool Math at Trouble Free Pool. Using my 6/3/22 data I am getting a CSI of -.13, so I am definitely doing something wrong. Do you happen to know the formula so I can plug into my spreadhseet?

I thought the ColorQ was off, but I get very similiar readings at two different pool stores (within 5-10ppm). The only calibration the instructions/website mention is to “blank” out the device before every use. I should have just gone with the drop method from Taylor…didn’t know they had tests that you didn’t need to interpert the color saturation.

My pool is clear. It is always clear, but I know that can be misleading, so that is why I keep detailed records of all my chemical readings. I was thinking about adding in 2 gal. of liquid pool shock (Sodium Hypochlorite 10-14%) to kill any organics that may be devloping in the pool. It is good to know that I need to accept the Chlorine/CYA Chart at Trouble Free Pool. You get so many conflicting or unclear FCL, TCL, and CCL recommendations wihtout regard to CYA. I was always afraid to get my FCL above 5. TPF forum really frowns upon chlorinators and provide much of their guidance on using daily routine of liquid chlorine (which is just not possible for me to maintain). For example, their Ideal Pool Levels for a vinyl pool are as follows:

PH

Min: 7.2

Ideal: 7.6-7.8

Max: 8

ALKALINITY

Min: 50-60

Ideal: 60-80

Max: 80-90

CALCIUM

Min: 0-50

Ideal: 50-550

Max: 550-650

CYANURIC ACID

Min: 30-40

Ideal: 40-50

Max: 50-60

I will have to drain and refill most of my pool water, but since the cost of doing this several times during the 4-5 month pool season is prohibitive, I usually wait till my CYA gets around 70 or 80 max. I will probbaly have to do this again one more time in August but at least that will be on a different bill (avoiding the surcharge rates). This is such a commoon problem with tablets, that you think they would figure out an appropriate ratio by now.

I tested my water again today and got the following results:

6/07/22: FCL 4.85,  TCL 6.25, CCL 1.4, pH 7.5, Alk 91, CH 155, CYA 62 - Thinking about shocking

I was surprised to see the CH levels remain static (actually increased by 5ppm). As expected the CYA increased, but I think this is being slowed by adding that 3-4 in. of water every week.

I will check the water again this weekend, and if the CCL level does not furhter reduce, then I think I will shock the pool on Sunday night…or do you think I should shock the pool now?

6

Hi J,

First, thank you for responding (still got no notification - need to check settings).

I should have been more explicit, but my sand filter is NEW. I did have a DE Filter.

My pool is vinyl, but the patio is pavers and there is a wall of stone with a waterfall. However, I do not use the waterfall as it needs to be replaced.

The plumbing shuld be PVC at this point (though I cannot be for certain for the main drain). It seems the piping was originally done with flex PVC. I was aiming for a 200 CH level due to the constant reduction in CH readings I was getting. I must have read somwhere that 100-200 is acceptable for vinyl. I guesss the good thing is that it is not a huuge concern, but still dont understand the significant CH loss. I checked out the Pool Math at Trouble Free Pool. Using my 6/3/22 data I am getting a CSI of -.13, so I am definitely doing something wrong. Do you happen to know the formula so I can plug into my spreadhseet?

I thought the ColorQ was off, but I get very similiar readings at two different pool stores (within 5-10ppm). The only calibration the instructions/website mention is to “blank” out the device before every use. I should have just gone with the drop method from Taylor…didn’t know they had tests that you didn’t need to interpert the color saturation.

My pool is clear. It is always clear, but I know that can be misleading, so that is why I keep detailed records of all my chemical readings. I was thinking about adding in 2 gal. of liquid pool shock (Sodium Hypochlorite 10-14%) to kill any organics that may be devloping in the pool. It is good to know that I need to accept the Chlorine/CYA Chart at Trouble Free Pool. You get so many conflicting or unclear FCL, TCL, and CCL recommendations wihtout regard to CYA. I was always afraid to get my FCL above 5. TPF forum really frowns upon chlorinators and provide much of their guidance on using daily routine of liquid chlorine (which is just not possible for me to maintain). For example, their Ideal Pool Levels for a vinyl pool are as follows:

PH

Min: 7.2

Ideal: 7.6-7.8

Max: 8

ALKALINITY

Min: 50-60

Ideal: 60-80

Max: 80-90

CALCIUM

Min: 0-50

Ideal: 50-550

Max: 550-650

CYANURIC ACID

Min: 30-40

Ideal: 40-50

Max: 50-60

I will have to drain and refill most of my pool water, but since the cost of doing this several times during the 4-5 month pool season is prohibitive, I usually wait till my CYA gets around 70 or 80 max. I will probbaly have to do this again one more time in August but at least that will be on a different bill (avoiding the surcharge rates). This is such a commoon problem with tablets, that you think they would figure out an appropriate ratio by now.

I tested my water again today and got the following results:

6/07/22: FCL 4.85,  TCL 6.25, CCL 1.4, pH 7.5, Alk 91, CH 155, CYA 62 - Thinking about shocking

I was surprised to see the CH levels remain static (actually increased by 5ppm). As expected the CYA increased, but I think this is being slowed by adding that 3-4 in. of water every week.

I will check the water again this weekend, and if the CCL level does not furhter reduce, then I think I will shock the pool on Sunday night…or do you think I should shock the pool now?

7

Hi J,

Do you happen to know the formula so I can plug into my spreadhseet?

I’ve seen the CSI formula but haven’t memorized it. It’s complicated. Test kits like the Taylor K2006 have a CSI calculator wheel where you can line up the water temp, PH, TA and CH and it will give you the CSI. But I don’t use that either. I use the Pool Math (by Trouble Free Pools) app. It has a section that will let you log the test results for FC, CC, TA, PH, CH and water temperature and it will automatically figure the CSI.

I should have just gone with the drop method from Taylor…didn’t know they had tests that you didn’t need to interpert the color saturation.

With the Taylor K2006 test kit the only test that you have to match to the color chart is the PH test. All the other tests change the color of the water sample. The Taylor K2006 uses FAS/DPD to test for chlorine and CC. It will give accurate chlorine readings of .2ppm or .5ppm depending on the water’s sample size. And it can read chlorine levels up to 50ppm.

My pool is clear. It is always clear, but I know that can be misleading, so that is why I keep detailed records of all my chemical readings. I was thinking about adding in 2 gal. of liquid pool shock (Sodium Hypochlorite 10-14%) to kill any organics that may be devloping in the pool. It is good to know that I need to accept the Chlorine/CYA Chart at Trouble Free Pool. You get so many conflicting or unclear FCL, TCL, and CCL recommendations wihtout regard to CYA. I was always afraid to get my FCL above 5. TPF forum really frowns upon chlorinators and provide much of their guidance on using daily routine of liquid chlorine (which is just not possible for me to maintain).

Why isn’t it possible to use chlorine to sanitize the water? Are you out of town a lot?

I was surprised to see the CH levels remain static (actually increased by 5ppm). As expected the CYA increased, but I think this is being slowed by adding that 3-4 in. of water every week.

If the water you are replacing is due to evaporation, that won’t slow the increase in CYA. CYA is only reduced by water being splashed out of the pool and replaced  or water being drained and replaced.

I will check the water again this weekend, and if the CCL level does not furhter reduce, then I think I will shock the pool on Sunday night…or do you think I should shock the pool now?

Since the CC levels are consistently above 1ppm, I think you should SLAM your pool. Since you are familiar with Trouble Free Pool, they have an excellent description of the process. You can read it here Here

Let us know if you have any other questions.

j

8

Thanks J!

I finally emptied and replace 75% of my pool water. I was then going to chock, but the numbers do not look to bad:

I started out with the following:

6/24/22: FCL 7.02,  TCL 8.24, CCL 1.2, pH 7.7, Alk 93, CH 136, CYA 63

Then I went to Leslie’s to double chek my numbers:

6/24/22 FCL 9.15,  TCL 10.50, CCL 1.4, pH 7.7, Alk 62, CH 118, CYA 71

I emptied and replaced 75% of my water:

6/28/22 FCL 3.57,  TCL 3.71, CCL .1, pH 7.5, Alk 64, CH 67, CYA 24

I will keep monitoring before I decide to SLAM.

My next issue is this water loss, so I contaced my local pool pros to help me figure out next steps with that. I hope once the water loss issue is resolved, things will bcome easier and less expensive to maintain.

Thanks again for all your help!

9

Hi Animal827,

According to the most recent test numbers the CCL is .1ppm. This tells me that you don’t need to SLAM the pool. 1 ppm or less is acceptable and those numbers show .1. Since you dropped the CYA level, the sanitizer is now doing it’s job and killing the chloromides. Hence the .1 ppm CCL. The test numbers show the CYA level is now 24ppm. This is low but the Trichlor you are using will raise that number in a short time. Just keep the FCL at 4 ppm. The best time to adjust the chlorine level is in the evening when the sun is goin down.

For the water loss issue, how much water are you losing.?

How hot does it get during the day? And how cool does it get overnight?

I ask these questions because unless you are losing like 3/4" - 1" of water a day, and it has been hot, it’s possible that the water loss is evaporation.

The temperature here has been in the high 80s to high 90s most of this month. As a result I am losing 1/3 to 1/2" of water per day. And when the temperature is that high, if it drops into the 70s overnight, you can lose as much water to evaporation overnight as you do during the day.

j