Daily FC loss

JW1

Well-known member
Sep 4, 2019
174
SW Ohio
With my pool uncovered without the solar cover I am losing 6.0 - 6.5 ppm of chlorine. I did the the OCLT last night and this morning and passed. I had my cya at 40 from my testing. I took a sample to Leslie’s a few days ago and they tested it at 33. I also took it to a small pool shop and they tested it as 40 with the sliding instrument. Two weeks ago I had a bit of cloudiness and I did a quick slam. The water has been crystal clear. But since then the temperatures have increased into the upper 80’s. Getting UV index of 8-10 for a few hours in the afternoon. The pool gets no shade at all. Water temp is approaching the mid 80’s. But I have to add LC twice in the afternoon because I’m afraid of getting too close to the bottom of my range. I added 9.6 of cya (sock method) yesterday to see I can bump to 50. I immediately bumped my FC to 8 in case I did. I will retest CYA today. I’m using fresh 12.5 LC dated 20131. I wish I could just test and treat once a day, but I can’t so far since it has warmed up the last two weeks.
 

bmoreswim

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Only two things consume FC. Sunlight and organics. Was your OCLT 0, .5 or 1? If it was 1, then I’d raise FC for a few days since you are also seeing high FC usage and had recent cloudness. If the higher FC usage continues then raise CYA to 60 and watch the FC usage. We are at the beginning of the 4 weeks of peak sun angle right now.
 

JW1

Well-known member
Sep 4, 2019
174
SW Ohio
I tested three times this morning with the same sample. I got 1.0, .5, and 0. I logged it as .5 loss. I just tested my cya after adding yesterday and I think it is now 50. Always a tough test to evaluate. No doubt at least 40, but I think it is 50. I will record and go with the higher cya and retest in a few days. Should I just target my high range of 8.0 or should I target just a bit more?
 

bmoreswim

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Bottom line is set it high enough so that it doesn’t go below the low end of the range, whatever that number needs to be. For now while evaluating, running higher FC perfectly fine. I tend to run higher than required FC all the time. Just my habit.

Any reason you are using liquid chlorine instead of a SWG? They’re the bee’s knees.
 

JW1

Well-known member
Sep 4, 2019
174
SW Ohio
Pool was installed last October so this is the first summer and a big learning curve. During our conversation with PB we asked about SWG, he didn’t recommend it. We decided to not get a SWG or heater for the first year and see how it goes. Studying this site I have purchased a robot from Marina along with using hairnets and scum-bug. Things are going well except daily chlorine loss the last two weeks. A lot of neighbors have ionizers and/or frog system so when I’ve walked the neighborhood and ask about their daily FC loss or cya levels, it is like I’m speaking a foreign language. I’m starting to see quickly the benefits of a swg instead of testing adding LC at 1 pm and 3:30 pm and 8:00 pm daily. Personally, it is not the amount of chlorine I have to add, but the multiple times I have to test and add to keep it in range.
 
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bmoreswim

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Until their pools or hair turns green, they are in heaven. :) Then they hit up Google and find TFP. 1.1M people came to see us last month!
 
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JW1

Well-known member
Sep 4, 2019
174
SW Ohio
I’ve been searching the forums and read the article titled TFPC for Beginners by JasonLion from 5/6/08. In the article it states “If you have a SWG or get extreme amounts of direct sunlight on the pool, adjust CYA to between 60 and 80. Otherwise adjust CYA to between 30 and 50.” It seems CYA can be my best friend or my worst enemy. Being this is my first summer as a pool owner, I’m trying to learn my pool. I know I must double check everything before increasing CYA further, but the full sun is just beating down on the pool all day long. The water looks terrific, but I think I’ll do another OCLT tonight/tomorrow to make sure I’m not missing anything. I’ve used the solar cover at night, I assume that does not interfere with the OCLT?
 

bmoreswim

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You seem to grasp the CYA concept. 👍 No, the solar cover is fine to use for an OCLT in this case. I might not use it if I were ending a SLAM and doing an OCLT.
 

JW1

Well-known member
Sep 4, 2019
174
SW Ohio
I think my surface area might be contributing to my FC loss to the sun. My surface area doesn’t match the smaller foot print with built in steps, walking ledge, and seats. I assume the sun eats at the surface FC. With full sun, no shade whatsoever, and larger surface area of pool water in relationship to gallons, I might need to take this CYA higher. Again, assuming I have passing OCLT clean water.
 

JW1

Well-known member
Sep 4, 2019
174
SW Ohio
My blue devil cya slider test arrived and I’m getting a reading of 20-30. It seems easier to read. Took a sample to Leslie’s yesterday and their system read a cya of 36, up from 33 the week before. Now I need to figure out how to proceed. I assume my dosing of LC based upon a cya of 50 could be incorrect and burning off too fast. I did pass my OCLT again this morning and passed. Water is crystal clear. Is it better to add cya or let FC to drop to 2 since that is the bottom of the 30 cya range? I might stick with 3-7FC range and retest CYA again with the slider test.
 

splashpad

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Aug 2, 2017
2,708
SE Kansas!
You are good to target an increase 10ppm for CYA when increasing (so as not to overshoot). With the higher FC loss, you might be one of the few overestimating your CYA :D I'd aim for a "true" 50 (with that much sun/UV light burning up your pool). But try to increase in 10ppm increments. PoolMath is your friend!
And Kudos @JW1 for not having bad habits to unlearn! Your pool neighbors will be jealous of your clear pool sooner than you think!
 
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djdonte

Well-known member
Mar 25, 2019
326
Houston, TX
In the hot Texas heat I had to bump my CYA up to 50-60 to lose 3-4ppm a day. That equated to me adding half a gallon of 10 percent per day. The sun really does a number on FC. ALWAYS stay on the high side of FC. The pool stores and other "experts" will tell you that any more than 4FC is harmful and that simply isn't true. A pool your size shouldn't need near as much liquid FC to maintain the proper levels.

Make sure you are doing the CYA test in sunlight. This test is a bit subjective and the hardest to get down. Also keep in mind the scale is parabolic not linear, so if you end up in the middle round up, its really hard to make out numbers that end in 5.

Lastly get a SWG. I did and I don't know why I didn't do it sooner. No more lugging cases of bleach from HD unless I need to slam. When I was adding bleach, a few times per year my CYA would get a little low so I would fill up my chlorinator with pucks and run it full blast for a week or two.
 
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Hootz

Bronze Supporter
Feb 5, 2018
258
Rogers, AR
Most of us struggle with the cya test and interpreting the results. I have a blue devil test as well and it helped me by seeing where the blue devil and tf100 tests agree. As others have stated the goal is not to let fc drop below the minimum. With liquid chlorine one always has to figure out how much to add so it does not drop below the minimum. It is your choice as far as cya levels. It makes sense to me to have cya as high as possible without causing trouble.
 
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JW1

Well-known member
Sep 4, 2019
174
SW Ohio
I just filled and placed a cya sock by one of the returns. The smaller amount of cya dissipates pretty quickly. I’ll will keep adding LC to stay within the 50 cya range for now and will retest tomorrow.

And I agree, a big SWG would probably make my daily pool routine a lot easier.
 
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LoneWolfArcher

Well-known member
May 29, 2019
378
Michigan
I’ve been searching the forums and read the article titled TFPC for Beginners by JasonLion from 5/6/08. In the article it states “If you have a SWG or get extreme amounts of direct sunlight on the pool, adjust CYA to between 60 and 80. Otherwise adjust CYA to between 30 and 50.” It seems CYA can be my best friend or my worst enemy. Being this is my first summer as a pool owner, I’m trying to learn my pool. I know I must double check everything before increasing CYA further, but the full sun is just beating down on the pool all day long. The water looks terrific, but I think I’ll do another OCLT tonight/tomorrow to make sure I’m not missing anything. I’ve used the solar cover at night, I assume that does not interfere with the OCLT?
That is interesting. I have dealt with high CYA for the last 3 years due to inheriting a pool (with a house buy) and having pucks. SInce I found TFP my CYA has come down from 120 to 90-100. One of the benefits has been, since my FC range is so big, I can bring it to the top of that range, and then I hold FC for two days in that range with direct sunlight (though I am in Michigan so our temps tend to be lower).
 
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JW1

Well-known member
Sep 4, 2019
174
SW Ohio
The Last few days has been very cool weather so I’ve kept the solar cover on about sixty straight hours and have lost very minimal FC. Today I took the cover off from 9 am to 1 pm to to clean the pool and lost 2 ppm of FC. Water is crystal clear. Placed the solar cover back on retested after sunset and lost nothing. It has to be the sun. I Plan on testing cya tomorrow as it will have been a week since my last sock addition of conditioner. My pool is full sun from probably 7 am to 8 pm.
 

djdonte

Well-known member
Mar 25, 2019
326
Houston, TX
Sounds like you are headed in the right direction. 2FC is not bad. Test your CYA and see how it goes. You will have to find the right balance of having enough CYA to prevent excessive FC loss but not too much to where you have to keep the FC really high, especially since you are manually chlorinating. For me I like to keep the CYA 30-40 in the colder months (which is still warm since I'm in Houston) and 50-60 in the summer. Since throwing out the pucks I notice I have to bump the CYA back up every month or two, so keep an eye on that as well. I think I was told heat can dissipate CYA, not sure though. My water is currently 90 degrees.
 

JW1

Well-known member
Sep 4, 2019
174
SW Ohio
I tested my cya this morning and it was between 40-50. Took a sample to Leslie’s and their result was 47. So after adding cya a week ago I now feel confident that is the correct range. Now time to take the solar cover and see how it responds. Suppose to get a few hours of nine on the uv index on this bright sunny day.
 

JW1

Well-known member
Sep 4, 2019
174
SW Ohio
So on Monday the pool was uncovered from 9am to 1 pm and I lost 2 ppm. Today the pool was uncovered from 9 am to 2:45 pm and lost 3 pm. So it possibly looks like a loss of 1 ppm per every two hours. I’m not sure how the uv index may correlate to fc daily loss? Monday had a high uv index of nine and today’s high was seven.