Cya Advice - Chlorine High

[dickeystorm]

Hi all,

I've had my pool for just under a year and have been going up and down with it. I've learned the hard way not to trust the pool store advice regarding chemicals. A few weeks ago I had whitish cloudy water. I had the pool store test the water since I don't have a good test kit yet. My chlorine levels had been between 3-5 but dipped to under 1 for a day.

July 9 readings:

FC 5.3

CC 5.3

pH 7.4

TA 80

CH 370

CYA 100

copper 0

iron 0

tds not run

Borates - not using

Advice was alkalinity was low add 16 lb 14 oz of sodium bi-carb, BioGuard balance pak 100, in 3 doses at least 8 hours apart which I did.

The cloudiness didn't clear. I was running the pump 4 hr/day at this time

July 17 I had the water tested again

FC 4.2

CC 4.4

pH 7.5

TA 144

CH 340

CYA 55

copper 0

iron 0

tds not run

Borates - not using

Advice was alkalinity was high, add 1 gal 2 qt 1 pt 14.75 oz muriatic acid in 3 doses 8 hrs apart. Did that.

Had an algae bloom. green. I shocked the pool with calcium hypochlorite, around 2.5 lbs. the green cleared slightly next day but was still green another day later. Back to the pool store for advice and fresh shock since the cal hypo was clumping and of unknown age and didn't seem to be working. Advice was shock and algaecide. July 22 added 3 lb super zappit and 1 qt algaecide plus (aqua chem, copper based) and ran pump 24 hr/day until clear which took the next 2-3 days.

This is when I discovered this site. I read the pool school and many posts and realized I shouldn't be using these chemicals and I have a better understanding of the chemicals now.

The water looks great now but the chlorine is still very high despite not adding any since last week. Today I had the pool store test the water.

FC 10 (the upper limit of their test capability)

CC 10

pH 7.5

TA 99

CH 310

CYA 70

copper 0.21

iron 0

tds 1400

Borates - not using

My concern now is 1) my chlorine is at least 10 a week after shocking with no additional chlorine added, when will it get back to safe swimming level. 2) is my cya too high keeping the chlorine high? should I lower cya? how? 3) is my hardness too high?

Sorry for the long post but best to get all the details out up front.

Thanks for the help.

[waterbear]

Hi all,

I've had my pool for just under a year and have been going up and down with it. I've learned the hard way not to trust the pool store advice regarding chemicals. A few weeks ago I had whitish cloudy water. I had the pool store test the water since I don't have a good test kit yet. My chlorine levels had been between 3-5 but dipped to under 1 for a day.

July 9 readings:

FC 5.3

CC 5.3

pH 7.4

TA 80

CH 370

CYA 100

copper 0

iron 0

tds not run

Borates - not using

Advice was alkalinity was low add 16 lb 14 oz of sodium bi-carb, BioGuard balance pak 100, in 3 doses at least 8 hours apart which I did.

The cloudiness didn't clear. I was running the pump 4 hr/day at this time

July 17 I had the water tested again

FC 4.2

CC 4.4

pH 7.5

TA 144

CH 340

CYA 55

copper 0

iron 0

tds not run

Borates - not using

Advice was alkalinity was high, add 1 gal 2 qt 1 pt 14.75 oz muriatic acid in 3 doses 8 hrs apart. Did that.

Had an algae bloom. green. I shocked the pool with calcium hypochlorite, around 2.5 lbs. the green cleared slightly next day but was still green another day later. Back to the pool store for advice and fresh shock since the cal hypo was clumping and of unknown age and didn't seem to be working. Advice was shock and algaecide. July 22 added 3 lb super zappit and 1 qt algaecide plus (aqua chem, copper based) and ran pump 24 hr/day until clear which took the next 2-3 days.

This is when I discovered this site. I read the pool school and many posts and realized I shouldn't be using these chemicals and I have a better understanding of the chemicals now.

The water looks great now but the chlorine is still very high despite not adding any since last week. Today I had the pool store test the water.

FC 10 (the upper limit of their test capability)

CC 10

pH 7.5

TA 99

CH 310

CYA 70

copper 0.21

iron 0

tds 1400

Borates - not using

My concern now is 1) my chlorine is at least 10 a week after shocking with no additional chlorine added, when will it get back to safe swimming level. 2) is my cya too high keeping the chlorine high? should I lower cya? how? 3) is my hardness too high?

Sorry for the long post but best to get all the details out up front.

Thanks for the help.

How are you testing the water? I would suggest getting a Taylor K-2006 test kit (FAS-DPD method, NOT DPD) which can directly test chlorine levels of up to perhaps 50 ppm without dilutions.

Also, with a CYA of 100 (and it could actually be much higher since it's difficult to measure CYY above 100 ppm) you need to maintain your FC at 8-15 ppm for normal chlorination and shock to 25 ppm or higher when you need to shock to end of with the same amount of ACTIVE chlorine in your pool because CYA binds with chlorine and lowers its activity. This link has more info.

You can run a high CYA pool but you do need a test kit that can test the higher FC levels needed (Taylor K-2006, not the K-2005) and must only used UNSTABILIZED chlorine. There is much evidence that you will actully use LESS chlorine doing this. As you have noticed, chlorine residuals in the water last much longer with higher CYA levels. If your CYA is between 100-200 ppm then 10 ppm is in the normal chlorination range and you can go in the water BUT you need to see just how high over 10 ppm your chlorine really is.

You can take a sample of pool water, dilutie it with an equal amount of DISTILLED water, test that for chlorine, and multiply your test results by 2. If the FC is less than 20 ppm I would have not problems with swimming in the water.

For right now your TA and CH are fine.

The ONLY way to lower CYA is to drain water and replace it.

[dickeystorm]

Hi all,

I've had my pool for just under a year and have been going up and down with it. I've learned the hard way not to trust the pool store advice regarding chemicals. A few weeks ago I had whitish cloudy water. I had the pool store test the water since I don't have a good test kit yet. My chlorine levels had been between 3-5 but dipped to under 1 for a day.

July 9 readings:

FC 5.3

CC 5.3

pH 7.4

TA 80

CH 370

CYA 100

copper 0

iron 0

tds not run

Borates - not using

Advice was alkalinity was low add 16 lb 14 oz of sodium bi-carb, BioGuard balance pak 100, in 3 doses at least 8 hours apart which I did.

The cloudiness didn't clear. I was running the pump 4 hr/day at this time

July 17 I had the water tested again

FC 4.2

CC 4.4

pH 7.5

TA 144

CH 340

CYA 55

copper 0

iron 0

tds not run

Borates - not using

Advice was alkalinity was high, add 1 gal 2 qt 1 pt 14.75 oz muriatic acid in 3 doses 8 hrs apart. Did that.

Had an algae bloom. green. I shocked the pool with calcium hypochlorite, around 2.5 lbs. the green cleared slightly next day but was still green another day later. Back to the pool store for advice and fresh shock since the cal hypo was clumping and of unknown age and didn't seem to be working. Advice was shock and algaecide. July 22 added 3 lb super zappit and 1 qt algaecide plus (aqua chem, copper based) and ran pump 24 hr/day until clear which took the next 2-3 days.

This is when I discovered this site. I read the pool school and many posts and realized I shouldn't be using these chemicals and I have a better understanding of the chemicals now.

The water looks great now but the chlorine is still very high despite not adding any since last week. Today I had the pool store test the water.

FC 10 (the upper limit of their test capability)

CC 10

pH 7.5

TA 99

CH 310

CYA 70

copper 0.21

iron 0

tds 1400

Borates - not using

My concern now is 1) my chlorine is at least 10 a week after shocking with no additional chlorine added, when will it get back to safe swimming level. 2) is my cya too high keeping the chlorine high? should I lower cya? how? 3) is my hardness too high?

Sorry for the long post but best to get all the details out up front.

Thanks for the help.

How are you testing the water? I would suggest getting a Taylor K-2006 test kit (FAS-DPD method, NOT DPD) which can directly test chlorine levels of up to perhaps 50 ppm without dilutions.

Also, with a CYA of 100 (and it could actually be much higher since it's difficult to measure CYA above 100 ppm) you need to maintain your FC at 8-15 ppm for normal chlorination and shock to 25 ppm or higher when you need to shock to end of with the same amount of ACTIVE chlorine in your pool because CYA binds with chlorine and lowers its activity. This link has more info.

You can run a high CYA pool but you do need a test kit that can test the higher FC levels needed (Taylor K-2006, not the K-2005) and must only used UNSTABILIZED chlorine. There is much evidence that you will actually use LESS chlorine doing this. As you have noticed, chlorine residuals in the water last much longer with higher CYA levels. If your CYA is between 100-200 ppm then 10 ppm is in the normal chlorination range and you can go in the water BUT you need to see just how high over 10 ppm your chlorine really is.

You can take a sample of pool water, dilute it with an equal amount of DISTILLED water, test that for chlorine, and multiply your test results by 2. If the FC is less than 20 ppm I would have not problems with swimming in the water.

For right now your TA and CH are fine.

The ONLY way to lower CYA is to drain water and replace it.

Waterbear, thanks for the reply. I am currently testing with a cheap oto kit (drops) which tops out at 5. I plan to pick up a good kit asap, I'm trying to decide between the tf-100 and the k-2006. The tf-100 seems to give more bang for the buck.

My latest test, from the pool store on July 30, is the bottom set of numbers showing the cya at 70. If I understand the chemicals right that means I need to maintain 7 for FC, correct? Also, if draining/replacing is the only way to lower cya how did my cya go from 100 to 55 to 70?

I don't really want to run high FC since I have a young child using the pool. I'll have to think about draining some.

I tested with the 50/50 mix of distilled water and it is still showing 5 or higher.

Thanks

[waterbear]

Hi all,

I've had my pool for just under a year and have been going up and down with it. I've learned the hard way not to trust the pool store advice regarding chemicals. A few weeks ago I had whitish cloudy water. I had the pool store test the water since I don't have a good test kit yet. My chlorine levels had been between 3-5 but dipped to under 1 for a day.

July 9 readings:

FC 5.3

CC 5.3

pH 7.4

TA 80

CH 370

CYA 100

copper 0

iron 0

tds not run

Borates - not using

Advice was alkalinity was low add 16 lb 14 oz of sodium bi-carb, BioGuard balance pak 100, in 3 doses at least 8 hours apart which I did.

The cloudiness didn't clear. I was running the pump 4 hr/day at this time

July 17 I had the water tested again

FC 4.2

CC 4.4

pH 7.5

TA 144

CH 340

CYA 55

copper 0

iron 0

tds not run

Borates - not using

Advice was alkalinity was high, add 1 gal 2 qt 1 pt 14.75 oz muriatic acid in 3 doses 8 hrs apart. Did that.

Had an algae bloom. green. I shocked the pool with calcium hypochlorite, around 2.5 lbs. the green cleared slightly next day but was still green another day later. Back to the pool store for advice and fresh shock since the cal hypo was clumping and of unknown age and didn't seem to be working. Advice was shock and algaecide. July 22 added 3 lb super zappit and 1 qt algaecide plus (aqua chem, copper based) and ran pump 24 hr/day until clear which took the next 2-3 days.

This is when I discovered this site. I read the pool school and many posts and realized I shouldn't be using these chemicals and I have a better understanding of the chemicals now.

The water looks great now but the chlorine is still very high despite not adding any since last week. Today I had the pool store test the water.

FC 10 (the upper limit of their test capability)

CC 10

pH 7.5

TA 99

CH 310

CYA 70

copper 0.21

iron 0

tds 1400

Borates - not using

My concern now is 1) my chlorine is at least 10 a week after shocking with no additional chlorine added, when will it get back to safe swimming level. 2) is my cya too high keeping the chlorine high? should I lower cya? how? 3) is my hardness too high?

Sorry for the long post but best to get all the details out up front.

Thanks for the help.

How are you testing the water? I would suggest getting a Taylor K-2006 test kit (FAS-DPD method, NOT DPD) which can directly test chlorine levels of up to perhaps 50 ppm without dilutions.

Also, with a CYA of 100 (and it could actually be much higher since it's difficult to measure CYA above 100 ppm) you need to maintain your FC at 8-15 ppm for normal chlorination and shock to 25 ppm or higher when you need to shock to end of with the same amount of ACTIVE chlorine in your pool because CYA binds with chlorine and lowers its activity. This link has more info.

You can run a high CYA pool but you do need a test kit that can test the higher FC levels needed (Taylor K-2006, not the K-2005) and must only used UNSTABILIZED chlorine. There is much evidence that you will actually use LESS chlorine doing this. As you have noticed, chlorine residuals in the water last much longer with higher CYA levels. If your CYA is between 100-200 ppm then 10 ppm is in the normal chlorination range and you can go in the water BUT you need to see just how high over 10 ppm your chlorine really is.

You can take a sample of pool water, dilute it with an equal amount of DISTILLED water, test that for chlorine, and multiply your test results by 2. If the FC is less than 20 ppm I would have not problems with swimming in the water.

For right now your TA and CH are fine.

The ONLY way to lower CYA is to drain water and replace it.

Waterbear, thanks for the reply. I am currently testing with a cheap oto kit (drops) which tops out at 5. I plan to pick up a good kit asap, I'm trying to decide between the tf-100 and the k-2006. The tf-100 seems to give more bang for the buck.

IF you are refereeing to this comparison chart be aware that I am the one who wrote it when I was a moderator at TFP before it changed hands and, FWIW, came up with "more bang for the buck" when promoting that kit for Dave because I was trying to help him get his test kit business off the ground.

http://www.troublefr..._kit_comparison

I wrote that chart to skew in favor of the TF100 but I do think the acid and base demand tests are extremely useful. In fact, I had mentioned to Dave more than once about adding them as an optional feature to the kit since demand reagents are available for the K-1000 series comparators.

I would recommend the Taylor K-2006 at this point. There is a real use for the acid and base demand tests and the pH test in the K-2000 series of kits (with the 44 ml comparator and reagent R-0004) is really superior to the K-1000 comparator and R-0014 used in the TF100. IF you already have an OTO test you do not need the one in the TF100.

Taylor also seems to have, IMHO, better quality control/fewer static problem on the dropper bottles and more uniform drop size, which is important in titration tests.

You realize that you can dilute your sample with distilled water to extend the range (with loss of precision) of your OTO kit (or a DPD kit for that matter).

1 part pool water 1 part distilled water and multiply your test results by 2

1 part pool water 2 part distilled water and multiply your test results by 3

1 part pool water 3 part distilled water and multiply your test results by 4

1 part pool water 4 part distilled water and multiply your test results by 5

My latest test, from the pool store on July 30, is the bottom set of numbers showing the cya at 70. If I understand the chemicals right that means I need to maintain 7 for FC, correct? Also, if draining/replacing is the only way to lower cya how did my cya go from 100 to 55 to 70?

Simple, testing error. It's very common in pool store testing,. To give you an an example, a store I worked n used LaMotte Waterline Express testing and there were 5 people besides myself that tested water. I was the only one that had taken and passed the LaMotte certification exam. I am not going to say that the others did not know what they were doing but there was a LOT of testing error and procedure error in testing that I personally observed. The goal of the water testing was to hopefully sell more chemicals to our customers every week when they came in with a water sample.

THIS is the main reason you want your own K-2006 and want to do your own testing.

I don't really want to run high FC since I have a young child using the pool. I'll have to think about draining some.

There is a fallacy in your logic because you really don't understand the chemistry of chlorine and CYA.

The amount of ACTIVE chlorine in the pool stays the same even though you are running higher FC with higher CYA levels and in fact, an unstabilized pool with FC at 2 ppm (not uncommon for an indoor pool) will have a higher level of ACTIVE chlorine in the water than a pool with CYA at 80 ppm and FC at 8 ppm. You have to have enough chlorine in the pool to combine with the CYA and still leave some behind in the water to sanitize and kill algae (chlorinated isocyanurates--compounds formed from chlorine and CYA--ARE a form of combined chlorine, btw. It's just one that can give up the chlorine again when it is needed. sort of like a clhlorine 'bank')

I tested with the 50/50 mix of distilled water and it is still showing 5 or higher.

this would be higher than 10 ppm so the next step is a 2 to 1 dilution and multiply the test results by 3.

Thanks