Passed the OCLT but still using allot of chlorine

[JimTMich]

Pool got away from me in a rainstorm and river birch dumping seeds in the pool. Started the SLAM as it was starting to get cloudy and using twice as much chlorine with nothing left at the end of the day..
Now 2 weeks later I'm still at slam level, been passing the OCLT since day 3 but the pool is still using 9ppm chlorine during the day of liquid. cloudiness is just about gone. Pump is running 24/7. Scrubbing daily.

FC 13 (been running it up to 20 after the sun goes down).
CC 0
pH 7.5
TA 180
CA 140
CYA 40
Water temp 83F

Why was I using 1/2 gal a day to maintain 6ppm and now I'm using 1-2 gal/day to maintain 14.

 

[jblizzle]

A simple way to think about it is that CYA protects a % of the FC from the sun. The higher you raise the FC, the more ppm you lose at the same %.

 

[YippeeSkippy]

..and you have a fairly large pool there. It just takes more of everything.

 

[duraleigh]

been passing the OCLT since day 3 but the pool is still using 9ppm chlorine during the day of liquid.

That doesn't work out. If you are consuming 9 ppm daily (that's about 4 times the average) you simply cannot pass the OCLT.

Chlorine is only consumed by two things....the sun and organics in your pool. The sun (with your CYA of 40 ppm) only takes about 2 ppm of FC so your other FC of 7 ppm is being consumed by organics.

You need to SLAM the pool.

 

[wjr75]

We never have had the river birch seeds as bad as we got them this year. They eat a lot of chlorine is all I have to say. They are done around here now.

 

[Pool Tool]

One other potential issue is your chlorine strength. Test before and 1/2 hour after you add chlorine tonight and see if it falls inline with what you are adding. I don't think this 100% of your problem and agree with Dave to continue your slam, but it could be a factor.

Are you pretty confident in your CYA result?

 

[kcindc]

You stated that the pool is still cloudy... you can't pass the SLAM criteria until the water is clear. All 3 criteria must be met for your to finish your SLAM. Pool School - SLAM - Shock Level And Maintain

You are done when:
CC is 0.5 or lower;
You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
And the water is clear.

 

[JimTMich]

This is an odd one.
Verified the cya at 35-40 yesterday. Fresh tft refill this spring so chemicals should be good.
I have been checking fc level before I add liquid bleach and after 1hour. Then again at 10:00pm and 6:00 am to get the oclt. It has been 0 to 1 ppm loss. So I have kept the slam going since it's not perfectly clear. Looking really good this morning. I could see the details in the liner in the 12' deep end.
I am continuing the slam. Have been dosing it up to 19-21 at night, verifying no loss in the morning, and it's coming down to 14-11 by the time I get home from work.

 

[JimTMich]

We never have had the river birch seeds as bad as we got them this year. They eat a lot of chlorine is all I have to say. They are done around here now.

Thanks for the feedback. That is probably what started it. I had two of the trees taking out this spring. Still have one left. I will make a note to do a better job cleaning those up next year.

 

[JimTMich]

Update, Went away for the 4th for a few days so I put 8 tri chlor pucks in the skimmer basket out of necessity. (brought CYA up to 50-60 range) Came back and the pool was crystal clear and still at slam level.
I am now back to 1/2 gal 12.5% (3ppm) usage per day.
So yes, in retrospect the slam probably wasn't finished and that is what was driving the usage up. I still have no idea why it wasn't using chlorine at night though.
Thanks for the help!
Jim

 

[Mr Bruce]

Please don't ever put pucks in the skimmer again. They are VERY acidic and can cause major damage. Use a floater if you are (temporarily) using pucks.

 

[pooldv]

+1 to no pucks in the skimmer. Buy a floater.

- - - Updated - - -

+1 to no pucks in the skimmer and using a floater.

 

[JimTMich]

Thanks for the comments. I have an inline puck feeder, but I didn't think It would produce enough to finish the slam while I was away for the weekend.....I also didn't want to pour in massive ppm of liquid. I chose the lesser of the evils I had available.
Definitely has me thinking about the convince of a SWCG for weekends away.....