Struggling With FC

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C

CJ7

0
Aug 2, 2018
41
Utah
I have a 9,000 gallon pool that I'm dumping an average of 1gal of 10% bleach in everyday. We had roughly a months worth of 100°F+ days with 10-12 hours of direct sunlight.

I've been bringing the pool to 12-13 FC each evening and test around 1.5-3 FC with a very light pink 0.5 CC test on average. Pool is crystal clear.

CYA: 90 (pool guy loved tabs and shock)

Any suggestions or am I just subject to high UV loss?
 
Your water may be clear, but I suspect you have excessive organic demands. It's not uncommon to happen when the CYA is as high as yours. Unfortunately, we can't blame it on the hot weather as we're all dealing with that one. :sun: At some point I suspect your FC dropped too low for that elevated CYA level and all you are doing is playing a yo-yo game with the chlorine now. There's no sense doing an Overnight Chlorine Loss Test because you're obviously losing more than 1 ppm of FC overnight. I would implement a SLAM Process. Of course you have the choice of increasing your FC to the SLAM/Shock level noted on the [FC/CYA][/FC/CYA] based on your CYA of 90, or you can exchange a little water to lower that CYA a bit. Last thought, if you have any doubt about the CYA that it could be slightly higher, you might consider doing a diluted CYA test as seen on the Pool School - CYA page starting at step #8.
 
Texas Splash said:
Your water may be clear, but I suspect you have excessive organic demands. It's not uncommon to happen when the CYA is as high as yours. Unfortunately, we can't blame it on the hot weather as we're all dealing with that one. :sun: At some point I suspect your FC dropped too low for that elevated CYA level and all you are doing is playing a yo-yo game with the chlorine now. There's no sense doing an Overnight Chlorine Loss Test because you're obviously losing more than 1 ppm of FC overnight. I would implement a SLAM Process. Of course you have the choice of increasing your FC to the SLAM/Shock level noted on the [FC/CYA][/FC/CYA] based on your CYA of 90, or you can exchange a little water to lower that CYA a bit. Last thought, if you have any doubt about the CYA that it could be slightly higher, you might consider doing a diluted CYA test as seen on the Pool School - CYA page starting at step #8.
Click to expand...

I'm not sure where the organic demand is coming from. I run the pool pump for 8 hours daily, the spa spills in to the pool. I run the spa jets for 15m daily as well, just to move water through the spa pump and lines.

I had started a SLAM, but it was not completed as I had to leave town.
 
I'm not sure where the organic demand is coming from.
Click to expand...
That's the tough part which is why as pool owners we have to exhaust all possible hiding places when treating a pool for suspected algae. Following that SLAM Process page thoroughly is key. Since you had to leave town and stop prematurely before, I suspect it didn't get 100% eradicated. Remember before you SLAM, lower the pH to about 7.2 first, the increase your FC to the proper SLAM FC level for your current CYA - see [FC/CYA][/FC/CYA].

If you have a ladder or steps that can be removed, it's best to remove them for cleaning and inspection. If you have a pool light set into a niche, remove the light and clean in that niche as well. Besides maintaining the proper FC level, it's all about the details. Good luck!
 
Thanks everyone. Just backwashed and did some inspection. Found some slimey stuff in the skimmer area.

Did a more comprehensive test:

FC: 6.5
CC: 0
pH: 8
TA: 170
CH: 450
CYA: 80 (diluted test)

Going to bring the pH down and do some swimming. I'll test again this evening.
 
Just tested. Dosed to 12 FC around 10pm last night.

FC: 6.5
CC: 0.5

WOW! I cleaned all pump baskets, skimmer and found the slime yesterday. I also opened the floor drains very slightly to run with the skimmer and vacuum during the pump run time.
 
CJ, tonight when you dose please wait about 30 mins and test to make sure you are reaching your goal number for the FC. Remember chlorine degrades so..........we don't want to take the chance it is really lower than you think.
 

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kimkats said:
CJ, tonight when you dose please wait about 30 mins and test to make sure you are reaching your goal number for the FC. Remember chlorine degrades so..........we don't want to take the chance it is really lower than you think.
Click to expand...

Tonight's measurements:

FC: 4.5
CC: 0
pH: 8.0

Added acid and tested 30m later.

FC: 4
CC: 0
pH: 7.4

Added chlorine to bring FC to 11 and tested 30m later.

FC: 14
CC: 0.5
 
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