OCLT fail?

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Anjayla0021

Anjayla0021

0
May 12, 2017
128
S. E Michigan
I don’t get it. I started my SLAM 6 days ago. Around day 4, my pool passed the OCLT, but since the water still looked a tiny bit cloudy, I kept going. Day 5 and water is crystal clear. I performed the OCLT overnight and it makes no sense to me. My reading at 10pm last night was 13.5 with cc of .5

At 6:30am I tested and got a 12 and then I retested immediately just to make sure I was accurate and I got an 11!

The pool water looks amazing. I’m not sure what to do. How can my water pass on day 4 but then 2 days later not pass? I feel I’m doing/did everything right and worry about the accuracy of the test itself. How could I get 2 different readings from the same water?

Advice?
 
The FC test you are performing requires that you continue to add drops until the last drop you add makes no color change WHATSOEVER.

That drop that had absolutely no effect is subtracted and the result is your FC.

Are you doing that?
 
I count my last drop that takes away absolutly all the pink color as my last drop...so yes, it sounds like I’m doing things right as one more drop that would have no affect would be subtracted. I even hold the vial up to white paper because I have noticed that the speedstir light can play tricks on my eyes.

duraleigh said:
The FC test you are performing requires that you continue to add drops until the last drop you add makes no color change WHATSOEVER.

That drop that had absolutely no effect is subtracted and the result is your FC.

Are you doing that?
Click to expand...
 
So if your two tests were 12 and 11, call the result 11.5 and you fail the OCLT and should continue the SLAM.

If you hold your FC at SLAM value today, you will likely pass the OCLT tomorrow AM.

You are close but your FC is still being consumed by some invisible residual organic material that you cannot see.

Stay the course until you pass all three criteria, then enjoy your swim season!

PS - don't worry about the precision of the test.....it works for thousands and thousands of us and it will work for you.
 
First of all, I agree with the comments above. You are close but not quite done. Stay the course and when you are done you'll find the OCLT passes easily. Most people rush to call it done but really they are just shortchanging themselves and risk a reoccurence of algae. At this point your pool looks great so start swimming and have fun! It's safe to swim up to SLAM level.

Now for some details answering your questions:

The amount of powder is not critical but if you don't use quite enough the pink color can be indistinct at the end of the test so it can be hard to see the transition to clear. Better to use plenty of powder than barely enough. At a FC=12 any reasonable amount of "heaping" should be enough though.

As for the accuracy of the test itself, best practice is to hold the dropper bottle vertical and let the drops hang for a bit before falling, maybe around 1 per second. If you do that, then about the only source of meaningful test error would be filling to the 10ml line in a sloppy, careless fashion (ie 9ml one time, 11ml next time) so pay a modicum of attention to getting the level the same each time and you'll be fine.
 
Would allowing the drops to mix in too fast cause issues? Should I not be squeezing the drops in?

Its now been a week and the darn pool still isn’t passing overnight. The water looks beautiful and I’m going to keep going, but when I do multiple tests on the same water sample, the results are never consistent. I’m pretty careful with my water measurement...the only thing I can think of is adding drops too quickly.

Another thing i noticed...while my water has been crystal clear for the past 3 days, when I backwash, it comes out almost an orange brown color for about the first 15 seconds or so. I backwash until the water comes out clear. Could something be in my sand filter? Would frequent backwashing maybe help me out at all?
 
The drops should appear to briefly hang and then fall. A drop each second is about the right pace. You should not be squeezing very hard.
Bottom should be completely vertical upside-down.
 
Finally passed the OCLT! Maybe I WAS dropping in way too fast.

11:15pm FC=15
7:00 am FC= 14.5 and CC = 0.5

Now that the pool passed its test, I need to get my CYA up as it was at 40 and with SWCG I need to be at 80. Should I adjust now? Or wait until FC comes down a bit?

Should any additional adjustments come now, or should I wait on those ones too with a lower FC?
 

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Add some CYA to target 70 now. In your climate that will be sufficient. Keep your FC based on CYA of 70 now using [FC/CYA][/FC/CYA].

Start your SWCG with the settings to create 3 ppm chlorine per day. I would do that now.
 
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