CYA of 50 & daily additions of 60 oz. or 4 ppm based on my pool

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Catanzaro

Catanzaro

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TFP Guide
Jul 30, 2014
3,508
Monmouth County, New Jersey
My current CYA reading is 50. The minimum FC is 4 and target is 6. I have been dosing the pool with 4 ppm per day, or 60 oz. based on the size of my pool. Every Saturday, I do the complete testing and average out the numbers to determine how much FC I have been losing daily. I have been keeping track of everything, including temperatures so I can understand my pool better.

It changes weekly. I have been burning off between 3.5 and 4 ppm daily. At the end of the week, If the FC levels are too high, I may then lower the dosage one day or skip if I am slightly higher than normal.

Even though the minimum is 4 and we try not to drop below this, does it make any difference if I drop to about 3 in the morning (around 6 a.m.) and then add enough liquid chlorine to bring up to 7, while gradually the FC is consumed and reduced back to around 3 by the next morning. My CC is always "0" to ".5", depending on swimming activity. Or should I increase the minimum so the drop would be around the minimum or between minimum and target. I know that it is safe to swim up to shock (SLAM) level, etc.

I am very religious in my additions and do make changes. Everything else has been perfect. No TA adjustments and only a 1X PH adjustment, outside adding CYA to bring from 30 to 50. The weather has been pretty consistent here in NJ, and I know that once the temperatures get into the 90's, and school is out that I will have to increase my chlorine additions and test at least 2X a week, as I could drop very quickly and have no chlorine or have CC consume all my FC.

Or should I start the day (after dosing the pool) at 10 FC and drop down to 6, or start at 8 and drop down to 4 FC. Any thoughts?
 
I agree with the OCLT to validate if anything is eating your FC. Without knowing all your pool habits, losing almost 4 per day seems a bit excessive. As you even suggested, I would increase my FC level slightly to ensure it never drops below the minimum. If it happened on a rare occasion, that's one thing. But when it does it consistently, you should adjust accordingly until you find the root cause of the drop. I commend you on your awareness of pool levels and being so proactive. Good job.
 
Yes, the children are all still in school until this Friday. Snow days affect attendance.

As for the water, it is crystal clear. With the filter shut off and the sun not shining on the pool and liner, it has this blue tint. I sometimes sit with a cup of coffee in the morning and just stare at the water as this is very relaxing. Friends that come over have said that the water in their pool does not look like mine. Chances are that they have bleached their liner and we know the rest of the story.

I have performed the OCLT and validated that there is nothing in the pool eating at FC. Tested at 10 p.m. and back at 6 a.m.

There are a few items that come to mind.

The 12.5% liquid chlorine may not be 12.5% and may have degraded. Although, I did call the manufacturer and spoke to them along with the pool company. The latest batch was fresh and just came off the truck when we were there.

Secondly, the size, or amount of gallons that I have in my pool may be off. The pool company never had the 17*33 pool, regarding gallons. They had 19*35 and it was just an estimate. My pool is 17' wide and it comes into a 13' wide in around the center and back to 16' wide by the diving board, with 3' in the shallow end and 8' in the deep end. Because it is vinyl, the sides come down to a point and not straight down like a concrete pool. The sun beats down all day on the pool as well. Very few leaves get into the pool as well. Even if my pool was 17,000 gallons (2,000 gallons more), the tracking error would be about .5 ppm.

One last and important item is that I do not dose the pool at night, but in the morning around 7 a.m., daily and maybe once a week around 8 a.m. I know that it is better to do this at night, but my schedule does not allow this each and every night. Each morning, after I wake up, the liquid chlorine is added. I use an old sweatshirt and gloves so there is not too much of a mess. Additionally, I dilute the bleach in 5 gallon buckets and pour slowly in front of a return. I understand that I would get my $$ worth, but I know exactly what the day is starting out like, which is more important to me. When the calculation was done for the whole season, the amount of $$$ and savings was not worth the stress of having to ask other family members to assist me in taking care of the pool during the evening when I am not around.


I feel that I have good knowledge about the TFP methodology as I spent at least a few hours a week reading the posts. Maybe, all 3 factors are contributing to the amount of FC that is used daily. I keep the boxes stored in the basement and in a dark cool place (at least the coolest part of the home). Lights are off at all times until I need to go get the chlorine.
 
My kid was out May 20th but goes back on July 31st!

I add in the morning as well. During periods of heavy use I will test and add in the evening if necessary.

Howell? Live there for a couple of years in the early 70's. Taunton Elementary?
 
This morning I tested the water and added 8 drops before clear. Subtracted 1 drop to 7. My FC is 3.5. Added 5 drops of R-003 and turned slightly pink and 1 drop of R-0871 and back to clear. FC reading is 3. Added 90 oz. of 12.5% liquid chlorine.

Waited 1 hour and performed the test. There is a lot of movement in the water so everything mixed properly. 19 drops. Subtracted 1 and multiplied by .5. Total is 9 and subtracted, .5 for cc for a total of 8.5. Up 5.5 in FC in 1 hour.

Based on the calculator, if I had 15,000 gallons, this would increase my level to around 9 FC. There is no sun so it was a good time to test. I added approximately 96 oz. of 12.5%. It appears that my pool is around 17,000 gallons assuming the 12.5% liquid chlorine has not degraded at all. Or it could be a combination of less chlorine and a few more gallons. The mystery remains. I will use the 17,000 mark to make sure that I add enough chlorine daily. Also, I have increased my minimum to 4 ppm.
 

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You are on top of it and are doing a great job!

Regarding the FAS/DPD testing, did the 8th drop make the water clear or did it go clear on the 7th drop. Once the water is clear do not add another drop of reagent, this is the amount of drops you need to use and multiply that number of drops by .5 which will be the FC. To get the CC you add 5 drops of R-0003 to see if any pink shows up. This is the CC amount and is determined by how many drops of R-0871 are added. Have you seen the Extended Test Kit Directions. This is a little nitpicking but I want to make sure you are doing the test correctly. It's the other tests that require an extra drop to make sure the color doesn't change. The FAS/DPD test goes from pink to clear and the drop that makes it clear is the final drop and is counted.

Double check the CYA and you might try bumping it up by 10ppm.

What is the pool temp?
 
Ping, the 8th drop made the water clear and I did not add another drop. Followed the same protocol the second time around. Then added 5 drops of R-0003, turned slightly pink and one drop of R-0871 for a CC reading of .5. There was not another drop to make sure the color did not change.

Before the last drop, the water had a slight pink to it. Then I added the last drop (drop # 8) to make it clear and subtracted the 1 drop to get the accurate reading. I have read that the last drop needs to be subtracted. Because the tests were performed in the same manner, the second time, the actual increase in FC was 5.5 ppm. The CC reading is easy to understand.

My CYA level is at 50 exactly. Water temperature this morning was around 78 degrees. It has been on the warm side here in NJ. If I catch 3 days of anywhere between 85-90 day temperatures, the water is around 84 degrees. There is no heater as the sun beats down on the pool all day, the dark liner helps and the circulation system moves water very well.

I have read the material many times and have helped people. Yesterday, I tested my neighbors water. He had algae, shocked his pool 2X and his CYA was 20. FC was 1 and CC was 0. He uses 3" tablets (of course) and the pool company sells him many items he does not need. I recommended TFP to him. It is truly amazing how many people do not know how to truly take care of pool and how much misinformation they have received over the years.
 
Catanzaro said:
Before the last drop, the water had a slight pink to it. Then I added the last drop (drop # 8) to make it clear and subtracted the 1 drop to get the accurate reading. I have read that the last drop needs to be subtracted. Because the tests were performed in the same manner, the second time, the actual increase in FC was 5.5 ppm. The CC reading is easy to understand.
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No need to subtract the last drop for the FAS/DPD test, there are other tests that require the last drop to be subtracted.
 
Catanzaro said:
This morning I tested the water and added 8 drops before clear. Subtracted 1 drop to 7. My FC is 3.5. Added 5 drops of R-003 and turned slightly pink and 1 drop of R-0871 and back to clear. FC reading is 3. Added 90 oz. of 12.5% liquid chlorine.

Waited 1 hour and performed the test. There is a lot of movement in the water so everything mixed properly. 19 drops. Subtracted 1 and multiplied by .5. Total is 9 and subtracted, .5 for cc for a total of 8.5. Up 5.5 in FC in 1 hour.

Based on the calculator, if I had 15,000 gallons, this would increase my level to around 9 FC. There is no sun so it was a good time to test. I added approximately 96 oz. of 12.5%. It appears that my pool is around 17,000 gallons assuming the 12.5% liquid chlorine has not degraded at all. Or it could be a combination of less chlorine and a few more gallons. The mystery remains. I will use the 17,000 mark to make sure that I add enough chlorine daily. Also, I have increased my minimum to 4 ppm.
Click to expand...

Your FC before adding chlorine was 3.5 ppm, not 3. The one drop to turn colorless after adding R-0003 just means CC <= 0.5 ppm. You do not adjust FC because of that (i.e. it's not 3.0, but still 3.5). Also as others noted, you do not subtract the last drop for the FAS-DPD test. You include the drop that has the sample turn colorless. So your FC is really 8*0.5 = 4.0 ppm before adding chlorine.

You then added 90 ounces of what you assume to be 12.5% chlorinating liquid. You then tested again. 19 drops * 0.5 = 9.5 ppm FC. So the rise is 9.5-4.0 = 5.5 ppm FC so that implies 16,000 gallons.

What was your overnight chlorine loss? For that test, I suggest you use a 25 ml sample size to get 0.2 ppm resolution, especially since you aren't SLAMing the pool. Assuming the loss is low, then 4 ppm FC loss during the day is very high. Your pool is behaving as if it doesn't really have 50 ppm CYA in it. Are you sure that the CYA test was done properly? Do you have the sun to your back so that the tube is shaded by your body in strong indirect light and that you look down into the tube in front of you?

Do you have any sort of system that could consume chlorine such as UV or ozone that likely only operate when the pump is running which would be during the day? I wonder if maybe you have something significant going on in your sand filter -- if so, then if you do the OCLT with the pump running overnight and you get a high chlorine demand, then I'd check your filter.
 
What was your overnight chlorine loss? For that test, I suggest you use a 25 ml sample size to get 0.2 ppm resolution, especially since you aren't SLAMing the pool. Assuming the loss is low, then 4 ppm FC loss during the day is very high. Your pool is behaving as if it doesn't really have 50 ppm CYA in it. Are you sure that the CYA test was done properly? Do you have the sun to your back so that the tube is shaded by your body in strong indirect light and that you look down into the tube in front of you?

I will double check the CYA tomorrow. I usually test on the deck with my back away from the sun. My testing is done early enough where the deck is shaded by the home. I am almost certain that I am doing the CYA test properly and it is 50.


Do you have any sort of system that could consume chlorine such as UV or ozone that likely only operate when the pump is running which would be during the day? I wonder if maybe you have something significant going on in your sand filter -- if so, then if you do the OCLT with the pump running overnight and you get a high chlorine demand, then I'd check your filter

The filter is only 2 years old. I have the basic sand filter and do not believe that I have any system that consumes with UV or Ozone. I will do the OCLT with the pump running tomorrow night and use the 25 ml sample for more accuracy.

Here is the schedule. The pump runs from 7 a.m. until 11 a.m. The chemicals are placed in the pool right after the pump turns on or I manually turn the pump on and add the chlorine if anytime sooner. The chemicals mix for at least 4 hours. Then the pump shuts off until around 1:30 p.m. and then turns back on until about 9:30 p.m. at night and then shuts off. The pool has sun all day from morning to evening. I do not believe there is anything going on here. My best guess is the 12.5% has degraded slightly, the amount of gallons in the pool and because I am adding the chlorine in the AM and not in the PM.

I have absolutely no idea where the margin and errors are.

How much FC should I be burning off daily without a lot of swimmer activity given the water temperature and NJ weather?

There is nothing on the boxes or gallons of 12.5% liquid chlorine that will tell me when the batch was produced. I called Seaboard Industries directly and they could not give me a straight answer. They get the shipment from somewhere and then it gets shipped to the pool company. I can only assume based on Chem-Geek's posts that after a certain amount of time how fast liquid chlorine degrades and that is my best guess. Thanks !
 
Normal FC loss per day for an FC/CYA ratio somewhat above the minimum is usually in the 2-3 ppm range. It is not unheard of to be outside that range, but it is unusual and usually means something is off -- too low a CYA level, too high an FC/CYA ratio, way too high a pH, or some unusual source of chlorine demand.

Since your pump is off from 11 AM until 1:30 PM the lack of circulation will mean that the sun breaking down chlorine will have the FC be much lower near the surface of the water than the average over the entire pool volume. However, it doesn't sound like you are testing during that window so that should be OK.

As for whether the 12.5% is degraded, that is checked by testing soon after adding it, say within an hour or even 30 minutes if you've got good circulation. You can then use such a measurement as a baseline at the start of the day.

The water temperature would only be a factor for the rate of chlorine loss oxidizing something or possibly a small amount of outgassing but such losses are usually quite low. If one uses a pool cover, one can get greater losses. The loss from sunlight during the day is only a function of the sun intensity and not water temperature.
 
Chem-Geek:

The test was done 30 minutes after pump turned on this morning at 6 a.m. It appears that the CYA is around 50. The black dot disappeared and it is hard to tell if the black dot is completely gone. At 40, it is definitely gone. Assuming I have a CYA of 40, does this make a difference? Should I add some more stabilizer to possibly bring up the level another 10 ppm?

Also performed the extended test using a 10 ml sample. Yesterday morning, after additions, I was at 9.5 FC. This morning I am at 6.5 FC, a total loss of 3 ppm for the 24 hour period. There was only a limited time of sun during the day, raining with no swimmer activity. I will perform the OCLT test this evening with a 25 ml sample. Based on what I am reading, I then multiply by .2. I will then test again in the morning to determine the OCLT overnight.

Attached are pictures from the liquid chlorine:

Is it possible that that the product was produced on 01-2014 and then sent out from the manufacturer on 07-2014. I have no idea on what I am reading. Please note that the gallon came from the white box.

IMG_0573.jpg

IMG_0572.jpg

IMG_0571.jpg

30 Minutes later (6:45 a.m.), the 10 ml. sample took 18 drops for a FC reading of 9. An increase of 2.5 ppm. I will wait another 30 minutes before testing to determine if the levels have increased. Maybe I tested too soon. BTW, I ordered extra reagent's for this test to make sure I can help other people this summer.

1 Hour later (7:45 a.m.), 18 drops for a FC reading of 9 with a CC reading of 0. Is it possible that the water did not circulate long enough before I did the first test? Or is 15 minutes enough time? This evening, I will perform the OCLT test around 9 p.m, when it is dark and post results.

At 12 p.m., 17 drops for a FC reading of 8.5.
 
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Just a thought here, based on my own experience with excessive chlorine demand, now resolved. Do you see any signs of grey fluff on the stair or ladder treads after the pool has been sitting for a while with the pump off? That was the tip-off for me. I thought I'd passed the OCL test and my water looked fine but this tiny trace of tell-tale algae kill in the mornings after the pool sat all night not running meant I just wasn't quite there yet (I add chlorine around dinner time and run the pump until 10pm). This resulted in a constant excess chlorine demand of 1 or 2 ppm daily. It is surprisingly difficult to completely eradicate algae in your pool once it gets into all the nooks and crannies. Again, just a thought.
 

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