Using too much chlorine

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HighWire

0
Dec 26, 2018
21
IL
I have the test kit that is recommended on here and do quick chlorine test every evening. Last night my test came back at 1, pool math recommends 6. So I added 172 oz of 7.55 bleach. Used more accurate test an hour later it as at 8, ok no big deal. This morning I checked the drop it was at 7.5, and cc less than .5. My cya on Sunday was 40, bumped it up to 47. Had a bunch of rain which is why cya was lower, had been running 47. Still needEd at least 1/2 ga per day before of 11.9%. Does this seem normal?
 
A 1/2 gallon of 12% chlorine in your size pool should increase the FC by about 3 ppm, so that is acceptable. When I was jug-dumping, it was always a 1/2 gallon of 10% in my 17.8K pool. But you definitely need to watch that FC level since an FC of 1 ppm is an invitation to algae. Hopefully you caught it in time since you seemed to pass an overnight loss test.
 
I opened the year at 30 ppm pf CYA. Once the heavy UV days of summer hit, I was losing as much as 5 ppm of FC per day. My pool is full sun with no deep end. I bumped CYA up to 40, and my loss was about 4 ppm on a very high UV day. So, I bumped to 50. I didn't see any significant change in FC loss to UV between 40 and 50 ppm of CYA.
 
Texas Splash said:
A 1/2 gallon of 12% chlorine in your size pool should increase the FC by about 3 ppm, so that is acceptable. When I was jug-dumping, it was always a 1/2 gallon of 10% in my 17.8K pool. But you definitely need to watch that FC level since an FC of 1 ppm is an invitation to algae. Hopefully you caught it in time since you seemed to pass an overnight loss test.
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The quick test in blue case was at 1, so I added enough 7.55 to get to 6. When I tested an hour later with the more accurate test it was at 8. Do you think the quick test could be off that much, like it went bad? It makes me wonder if it was really at one or if it was actually 3 or more.
 
Chasarms said:
I opened the year at 30 ppm pf CYA. Once the heavy UV days of summer hit, I was losing as much as 5 ppm of FC per day. My pool is full sun with no deep end. I bumped CYA up to 40, and my loss was about 4 ppm on a very high UV day. So, I bumped to 50. I didn't see any significant change in FC loss to UV between 40 and 50 ppm of CYA.
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Thanks that eases my mind a bit.
 
Texas Splash said:
The quick OTO color viewing block CL test is ballpark and combines both FC and CC, so it's really just to test for the presence of chlorine. The FAS-DPD is always much more precise.
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The kit says to test with FAS-DPD weekly, and the viewing block daily? Is that the way to go? Is the viewing block a good way to see how much chlorine to add everyday?
 
HighWire said:
The kit says to test with FAS-DPD weekly, and the viewing block daily? Is that the way to go? Is the viewing block a good way to see how much chlorine to add everyday?
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If you need to maintain an FC higher than 5 ppm per the FC/CYA Levels, then you have to use the FAS-DPD. Now if you happen to only need an FC of 3-5 ppm, you might get by with just the OTO to save on the powder and drops. Some people get so good with the OTO viewer they can interpret an FC higher than 5 when it goes from yellow to orange then brown. Me, I just use the FAS-DPD. It's accurate and easy. :)
 

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Once you 'train' your eyes to see the shade of the OTO color versus the FC you expect based on repeated FAS-DPD tests, then you can use the OTO daily and do the FAS-DPD at least a few times per week. Not sure I would go to once per week.

I never use the OTO. With a SWCG, I know the chlorine is being added every day. I test with FAS-DPD every other or third day. But in reality, I can look at the water and tell if it is good or not.
 
One more question. When I do the FAS-DPD test, I use the speed stir. After I add powder and water is red, I add the drops. It will turn clear for a few seconds then have a red tint to it. If I add one more drop is turns clear and stays. Which is the accurate one? I realize it is only .5 difference but curious?
 
HighWire said:
The sight test tube in kit, wasn’t quite 50 so an educated guess.
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The scale on the CYA tube is logarithmic and not linear. There is really no easy way to read in between the lines on the test tube. If a CYA reading falls between the lines, always round up and dose according to the FC/CYA Levels.
 
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