Combined chlorine

jmtaylor1228

Member
Oct 20, 2020
19
Central NJ
Hi all,

I have insanely high combined chlorine and it seems the more FC I add the higher it goes. I have a new pool that was green two weeks ago. I had a slightly green pool before the PB started the system (vinyl). For 1.5 weeks now I have been slamming testing every 2 hours except at after 9 and before 5. I get up at 5 and the pool is still at slam levels. I use the TF100.

cya- 40 (I tested it and my wife has tested multiple times). We added stabilizer per pool math and so we know it is correct.
Fc- 21 as of this morning (I went above slam level to try and ignite the CC) but the CC only increased
Ph- 7.2 at start of slam
CC- dark orange in the Taylor test kit was yellow three days ago when my FC dipped down to 13 (just below slam level) too high to even count. This morning it had a chlorine smell. I went back to slam and the color darkened.

the pool is so clear that I have been asked by neighbors how I am doing it.

no other chemicals are added except liquid chlorine.

I cleaned the return lines and light sockets prior to the lights being installed and the skimmer using both rags and a toothbrush. I clean the skimmers twice a week. I only use a rag and toothbrush nothing on it.

at this point I am in a total loss and frustration. The only relationship I see is a higher CC coinciding with the increase in high FC.

reading threads and pool school this should not be happening.
 

jmtaylor1228

Member
Oct 20, 2020
19
Central NJ
I thought I was doing the test wrong too. But my neighbors who use the TF100 for a while ran the tests and confirmed the results and were just as puzzled as I am. Neither of us can understand why it is almost orange in color when doing the CC and FC for 5 days has been at slam level or higher. I can understand the FC maybe losing more than 1ppm as I test 2 hours after the last add so maybe I am off there. But to get yellow one day when the FC dropped to lower level of slam and look to improve only to go orange after more Liquid chlorine is added and Fc level increased is a puzzle.
 

jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,856
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
Are you using the FAS-DPD test? This one does not use the yellow comparator block. You add R-0870 powder to a 10 mL sample, then count drops using R-0871 and multiply by 0.5 to get FC. Then you add 5 drops of R-0003 and count drops of R-0871 and multiply by 0.5 again to get CC. Both parts of this test the sample should go pink or red to clear.

Yellow and orange colors sounds like R-0600, which is for the OTO chlorine test which cannot be used as part of the SLAM.
 

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jmtaylor1228

Member
Oct 20, 2020
19
Central NJ
Thanks. It was early and I meant Total not combined. I thought the OTO also had to be .5 and that was killing me. The CC is .5 just tested again. Had I put that number in I would have caught myself earlier and avoided all of you the trouble.

I am guessing I can let the FC fall back to normal levels and that is why the OTO was turning yellow when I had a lower FC level, but orange with the High FC.
 
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jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,856
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
Yeah the OTO measures only TC, and the scale only goes to 5 ppm, so it cannot be used during a SLAM. It's great for quick daily tests to make sure there's enough chlorine, but the FAS-DPD is the only test that works during a SLAM. The FAS-DPD should also be used for regular testing to make sure things are looking good.
 
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