OCLT and testing consistency

[dspille]

I have been lurking for a while now, and I have been on BBB for a couple of months now. This site is an awesome resource, and the people are great! Thanks so much!

After getting a lot of rain the past few weeks, I became concerned after seeing what appeared to be the beginnings of algae growth, in spite of never allowing FC to drop below 5. It looked like grey dust on the bottom that would disappear when brushing. It also felt neither slimy or gritty, so I decided to go ahead and SLAM and have done so for the last four days. After the first day of SLAMing, no more sign of "algae", and I have continued to maintain shock level until last night. Filter has been running 24 hours/day. The pool has been looking crystal clear through the entire SLAM process and continues to look great.

My test results this morning:
FC 16
CC 0
PH 7.5
TA 100
CH 280
CYA 50-60 (I'm assuming 60)
Borates 40-50

Also, I lowered PH to 7.2 before starting the SLAM process

Now for my real question. Last night my FC was 14 (CC 0), and I did not add any chlorine to the pool, yet it read 16 this morning. Any ideas why FC would read 2 ppm higher? I have tried to be careful with my testing, always taking the sample about a foot deep in front of the skimmer. I am also trying to be careful with the drops to make sure I don't go too fast or too slow (no more than about 1 or 2 per second). One other important fact is that I installed a HASA Liquidator a couple of weeks ago, but I have had it shut off during this entire SLAM process (the flow indicator is at zero and I see no water movement in the 3/8" tubes).

Thanks,

Dennis

 

[Bama Rambler]

It's most likely some sort of testing error. Either you didn't wait quite long enough after the last chlorine addition last night or you stopped a drop or two short last night and ran a drop or two over this morning. The lighting was different, etc..

I'd run it again tonight and see what happens.

 

[BoDarville]

Welcome to TFP!

The most likely possibility is you are doing the evening FC test too soon after your last dose. You should give the chlorine about 30-60 minutes to circulate before testing.

 

[dspille]

I haven't dosed since yesterday morning, so it's likely a testing error. I will try again tonight.

 

[woodyp]

I think you whipped the algae...beat it into submission..........and it just "threw up" the extra FC in admitting defeat! At least I hope so.

 

[dspille]

I think you whipped the algae...beat it into submission..........and it just "threw up" the extra FC in admitting defeat! At least I hope so.

:lol: I hope that truly is the case, but I will try again to be sure.

 

[duraleigh]

dspille,

Make sure you are taking the test to it's completion....adding one last drop that does not make ANY further color change and then subtracting that drop.

 

[dspille]

dspille,

Make sure you are taking the test to it's completion....adding one last drop that does not make ANY further color change and then subtracting that drop.

I had not been doing that, but I certainly will from now on. Thanks to you all!

 

[dspille]

dspille,

Make sure you are taking the test to it's completion....adding one last drop that does not make ANY further color change and then subtracting that drop.

Dave,

Does adding that one last drop impact the combined chlorine test in any way? i.e. will that extra drop prevent the test from turning pink and throw off your CC drop count?

Dennis