Excessive Chlorine Usage (5 to 6 ppm per day)

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newbie2017

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Jun 26, 2017
71
Tulsa, OK
Since opening the pool (equipment was off, no cover), there has been excessive chlorine consumption.

The pool was closed (no cover) over the winter. Opened and there were spots of green algae. Brushed, cleaned and brought chlorine to shock level.

Water is very clear. Passed OCLT. But the chlorine consumption is very high. Been adding more than a gallon each day and keeping the chlorine at 10 ppm to account for the huge usage.

Yesterday the usage was 5.5 ppm. Should we bring up the CYA? I am planning on doing the OCLT again. Any other pointers?

Chlorine is a fresh batch. Tested after addition and it was at the right level.

CYA 50
CC 0.5
PH 7.5
TA 110
CH 175

Thanks
 
newbie2017 said:
Should we bring up the CYA?
Click to expand...
No, not yet. Excessive FC loss could be any of the following:
- Low CYA; your CYA, if tested accurately, if not low. I would not add anymore right now.
- Algae; even if you passed the OCLT, something is eating chlorine
- Old reagents causing testing error
- Human error in testing; inconstancy in water sample location or drops
- Old chlorine that is not providing a reliable FC goal

It might be good to do another OCLT. Before that, be sure to inspect all areas of the pool very carefully since we know algae can hide in all kinds of places (Behind lights with a niche, under a drain cover, etc) or anything else submerged in the water.
 
Did the OCLT again. There was a 0.5 loss. CC was at 0.5. The usage yesterday was again at 5.5 ppm. :(

I am planning to test the CYA again when there is enough sun. It would mostly be 50 or 60 (considering the way my eyes see.)

-- Chlorine reagents are fresh.
-- I tested after chlorine addition last week, and it was at the desired level. So, chlorine is also good.

Would there be algae lurking around anywhere even if we pass the OCLT test?

At my wits end :(. Any other pointers?

Thanks.
 

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Texas Splash said:
It really makes no sense to loose that much chlorine during daylight hours and none at night. Very odd. Are you 100% sure about that CYA?

I guess me and Lee were typing at the same time. Ears were burning.
Click to expand...
CYA to my knowledge did feel accurate. What is the number I should be at?
cowboycasey said:
I would say your CYA is 40... Was your CYA at 50 last year?
Click to expand...

Last August it was at 60. (Started off at 40, and brought it up to 60 over the course of 3 months)
This March, it was at 50. Tested twice this month, 50.
 
newbie2017 said:
Tested CYA few days ago. It is a cloudy day today and rain tomorrow. So, will test again when the sun comes out.

I definately saw the dot at the 60 mark. 50 - was a bit of a strain. At 40 - definately gone to my eyes.

So decided to keep it at 50. Am I doing it right?
Click to expand...
In this case I too would pinpoint the CYA at 40 as you saw the dot at 50. A large FC drop is understandable with a CYA of 40 and a fair amount sunlight. Personally, I’d retest and I’m guessing you’ll be adding more CYA
 
Well, we are not surprised to see CYA drop by about 5 ppm per month, so if it was 60 last year, and you felt confident at 50 earlier this year, you're probably right around that 40 range as Casey and Lee noted above. Can you have algae and still pass an OCLT? .... it's rare but I would have to say yes. Not very common at all, but I have seen it occur. So let's ask you this:
- This time of year, do you get enough heat and direct sunlight with the intensity that might warrant increasing the CYA to 50? That's a big driver as to what to do next. If you believe so, then you could increase the CYA to 50 and see if that helps reduce FC loss. The only problem there is if you still lose FC during the day, it's not from the sun and a SLAM is back on the table at a higher FC level (20).

If you opt for more CYA (50) and end-up doing another SLAM, here's what I would recommend at that point:
- Do the filter deep clean and referenced above.
- Remove the light again to expose the niche
- Take the FC up to SLAM level (20) and do all the normal SLAM tasks of brushing, etc. Just look around to ensure you didn't miss something.
- Once you pass that SLAM, take it up to Mustard Algae level for 24 hrs only (no swimming) - which is an FC of 29.
- After the 24 MA treatment, let the FC fall and monitor.
 

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