Question about testing and OCLT

Mar 17, 2010
1,088
Spring, TX
I have a question about the FC and CC testing in reference to the OCLT. Is there a way that the FC gets too high and it becomes unreliable?

My shock level is 20 and I have been having trouble getting my pool gallons correct for a while now and I may have the amount now. So anyways my FC last night was 30 after adding bleach. After the calculation in reference to the FC levels and bleach added I believe my pool is around 10,000 gallons. I am goin to keep experimenting with it. Is this a good way to determine pool size by doing this?

Anyways I kept seeing green in my pool daily and was like I have passed OCLT test with no issues. But I was under the asumption that my CYA was only 40 so I kept a target of 5. I measured it and I am at a CYA of 50 and my FC had been fallling under 4 daily which is the min for CYA of 50 so I am sure that is how the green is going.

So I did not pass the OCLT since I lost 4 PPM, but the water is very clear so I know I still need to shock. I guess the good thing is my cholorine level is high enough to where I will not have to add more cholorine more than likley but we shall see.

Test results

5/1/12 5/15 PM

pH-7.5
FC-4
CC-0
TC04
TA-80
CH-300
CYA-50

Added 3 182 oz bleach around 8:00 PM

Testing FC around 9:30-9:45 PM

FC-30
CC-.5
TC-30.5

Testing FC this morning around 7:15 AM

FC-26
CC-.5
TC-26.5

So I guess back to my original question is there a way that the FC gets too high and it becomes unreliable?
 
When the FC level is high it is important that you have consistent testing technique, hold the titrant bottle vertically, let the drops fall from the tip naturally instead of spraying them out, and so on. But all of that is fairly easy to master and once you have the test remains valid even when the FC level is quite high.

This does not apply to your situation., but the OCLT is not valid when the CC level is very high. You shouldn't even bother trying to do the OCLT test when CC is very high.
 
JasonLion said:
When the FC level is high it is important that you have consistent testing technique, hold the titrant bottle vertically, let the drops fall from the tip naturally instead of spraying them out, and so on. But all of that is fairly easy to master and once you have the test remains valid even when the FC level is quite high.

This does not apply to your situation., but the OCLT is not valid when the CC level is very high. You shouldn't even bother trying to do the OCLT test when CC is very high.

This testing method made a very big difference in my results, thanks for that info. Hopefully I pass the OCLT test in the AM. But testing today I had 0 CC, so that is an improvement.
 
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