Question on overnight chlorine test

[CurtB]

Hi,

I've been using the TFP protocols for a few years now and I think I may have messed up this year on the overnight test and that is why my pool is still cloudy. In order for the test to be valid and also the cc reading to be accurate I'm thinking the chlorine ppm must be in shock value level or above? If you do the test with the chlorine ppm under the shock value then I'm thinking that it may not drop overnight even though you still have algae because the level isn't high enough for the algae to consume the chlorine. Also the cc's wouldn't show up for the very same reason that the algae isn't being killed. Am I thinking correctly here? Thanks.

 

[Texas Splash]

I'm thinking the chlorine ppm must be in shock value level or above?

It's understandable to think that way. We've had numerous discussions behind the scenes here about the OCLT process. But as noted on the TFP Pool School - Perform the Overnight FC Loss Test (OCLT) page, the FC must simply be above 3ppm. Now if someone is currently doing a SLAM, then their FC should indeed be at SLAM level, but for those simply doing the OCLT as a diagnosis, it doesn't have to be that high.

 

[domct203]

Hi,

I've been using the TFP protocols for a few years now and I think I may have messed up this year on the overnight test and that is why my pool is still cloudy. In order for the test to be valid and also the cc reading to be accurate I'm thinking the chlorine ppm must be in shock value level or above? If you do the test with the chlorine ppm under the shock value then I'm thinking that it may not drop overnight even though you still have algae because the level isn't high enough for the algae to consume the chlorine. Also the cc's wouldn't show up for the very same reason that the algae isn't being killed. Am I thinking correctly here? Thanks.

It is not a requirement of the OCLT to be at shock level. It just so happens that most OCLT's are done during a SLAM.

If one is just checking for organics in the pool, the OCLT should be done at regular maintenance levels for your CYA level.

In other words, to check it at your daily FC target level is fine.

- - - Updated - - -

Whoops, Pat beat me to it (as usual ).

 

[CurtB]

It's understandable to think that way. We've had numerous discussions behind the scenes here about the OCLT process. But as noted on the TFP Pool School - Perform the Overnight FC Loss Test (OCLT) page, the FC must simply be above 3ppm. Now if someone is currently doing a SLAM, then their FC should indeed be at SLAM level, but for those simply doing the OCLT as a diagnosis, it doesn't have to be that high.

OK, thanks. I did my first test in SLAM mode as it dropped only 1ppm and showed 0 cc's, then I did the second test at 12ppm and it showed no drop and no cc's so I figured I was good. Then I didn't stay in SLAM mode and figured the filter would clear up the dead algae but it's not happening after close to two weeks so I'm bringing it back up to shock to see if it will clear as that is what Dave suggested. Then I got thinking about the OCLT and figured I would ask.

- - - Updated - - -

It is not a requirement of the OCLT to be at shock level. It just so happens that most OCLT's are done during a SLAM.

If one is just checking for organics in the pool, the OCLT should be done at regular maintenance levels for your CYA level.

In other words, to check it at your daily FC target level is fine.

- - - Updated - - -

Whoops, Pat beat me to it (as usual ).

Thank you for the reply as well!

 

[rkeller62]

Sounds like you never actually completed the SLAM. You met 2 of the 3 criteria, but if your water wasn't clear you never met the 3rd criteria and should have continued the SLAM until the water was clear.

 

[CurtB]

Sounds like you never actually completed the SLAM. You met 2 of the 3 criteria, but if your water wasn't clear you never met the 3rd criteria and should have continued the SLAM until the water was clear.

Yep I realize that this year. Before I would just let the chlorine drop after passing the tests and then my filter would clean it up but this year it's not happening. I always thought logically what's the point of keeping the levels that high if the algae was dead but I guess passing the tests doesn't always prove the algae is all gone.