waterbear
07-02-2013, 10:25 AM
Not sure I'm following you... Do you mean I should read the oto test after 10 minutes and that should give a tc reading that will match immediate dpd results?
Yes
Also, I don't know if this adds another piece to the puzzle or confuses things further, but I just tested the CL again about an hour after adding 192oz of bleach. I pulled a sample from the pool in a measuring cup like I always do and ran the same dpd test 4 times with 4 completely different results:
1. Fc 5, when I added r-0003 for cc the sample turned a light yellow, not pink. I have had this happen once before, so I retested (assuming I did something wrong)
DPD bleachout caused by high chlorine levels
2. Fc 22, cc 1.5... Huh? Retest again...
Probably close to what your levels actually are but still bleaching out a bit.
3. Fc 7, cc light yellow/peach????
DPD bleachout caused by high chlorine levels!
4. Fc 15, cc 7
All 4 tests were done within minutes from the same sample of pool water, and I rinsed with filtered water between tests. This stuff should be pretty simple, and I'm a pretty smart guy, but I am completely lost here.
Try diluting a sample of pool water with an equal amount of distilled water and testing that with the FAS-DPD test and multiply that test results by 2 to see what you get.
Re: the autocover...are you leaving the pool uncovered? If a pool is kept covered it is not uncommon for there to be a persistent high CC problem since there is limited offgassing of the disinfection byproducts and exposure to sunlight also is an integral part of the process of destroying CC (which is why persistent CC is a problem in most indoor pools!)
Yes
Also, I don't know if this adds another piece to the puzzle or confuses things further, but I just tested the CL again about an hour after adding 192oz of bleach. I pulled a sample from the pool in a measuring cup like I always do and ran the same dpd test 4 times with 4 completely different results:
1. Fc 5, when I added r-0003 for cc the sample turned a light yellow, not pink. I have had this happen once before, so I retested (assuming I did something wrong)
DPD bleachout caused by high chlorine levels
2. Fc 22, cc 1.5... Huh? Retest again...
Probably close to what your levels actually are but still bleaching out a bit.
3. Fc 7, cc light yellow/peach????
DPD bleachout caused by high chlorine levels!
4. Fc 15, cc 7
All 4 tests were done within minutes from the same sample of pool water, and I rinsed with filtered water between tests. This stuff should be pretty simple, and I'm a pretty smart guy, but I am completely lost here.
Try diluting a sample of pool water with an equal amount of distilled water and testing that with the FAS-DPD test and multiply that test results by 2 to see what you get.
Re: the autocover...are you leaving the pool uncovered? If a pool is kept covered it is not uncommon for there to be a persistent high CC problem since there is limited offgassing of the disinfection byproducts and exposure to sunlight also is an integral part of the process of destroying CC (which is why persistent CC is a problem in most indoor pools!)