Unable to pass OCLT

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Xdsxc

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Sep 5, 2013
2
Hello everyone - I've been having issues with passing the OCLT. This is my 4th night failing despite following it almost exactly. I've added over 20 gallons of
10% sodium hypochlorite and my results haven't even really been improving, but the pool itself looks crystal clear. I washed out the cartridge filters completely, and I took apart and cleaned the lights and the drains in the spa that I saw some algae growth behind. I've been brushing and vacuuming every day. But every night I've been losing about 4-5ppm of free chlorine. For example, I tested it this night and had 20ppm chlorine at 8:00pm, and only 15 at 12:05am. What else am I doing wrong? Could it be from the leaves and other junk being blown into the pool due to crazy winds lately?

17,000 gallon pool
CYA: 30
pH: 7.4 (from before bringing the chlorine high)
CH: 370
TA: 100

Thanks!
 
Hi Xdxsc. . . . Welcome to TFP! :)

Are you using one of the approved test kits to get your results? You need to add your pool equipment in your signature so the experts can help you solve your issues. Your location-region, state, etc. helps as well.

Check your ladder or remove it from the pool if you can. Remove any "floating things" from your pool, these areas are a breaking ground for algae.

With that said, be patient. You may need to raise your CYA to get the results you want. One more thing . . . . Did you SLAM your pool? All this information is in the pool school.
 
When you perform the OCLT, you do so to determine if there are organics in your water....demonstrated by the overnight loss of FC in excess of 1 ppm. That's what's happening in your pool.....you still have organics in the water.

Keep your FC at SLAM value. When the organics have all been removed, you will pass.

You are not doing anything wrong....just stay the course.
 
in only 4 hours of no sun. (8PM to 12 AM) 5ppm loss is a lot.


What was the condition of the pool before starting the slam?

Its hard to tell from your original post how many days you've been SLAMing your pool. It says you failed the OCLT test 4 times. Have you been shocking for many days before trying the OCLT tests or have you been SLAMing for only 4 days?

If you've only been SLAMing for 4 days that's a bit on the short side to be able to completely kill algae and remove it. Given your 5PPM loss in 4 hours without sun, leads me to believe your just not finished with the SLAM process. Also given that you've seen algae behind lights and jets, there could be more your not seeing that is playing a roll in this.

I would say give it 2 more days of SLAMMING, check lights, filters, ladders, and anything else and then give us an update.
 
To the experts: Is there a minimum amount of time for what TFP considers a proper OCLT test?

I have no facts or proof, but I would suspect most OCLT tests are closer to 8 hours from test to test. I've never seen it mentioned but is 4 hours enough to get a reading for Over night chlorine loss?
 
scott.MI said:
To the experts: Is there a minimum amount of time for what TFP considers a proper OCLT test?

I have no facts or proof, but I would suspect most OCLT tests are closer to 8 hours from test to test. I've never seen it mentioned but is 4 hours enough to get a reading for Over night chlorine loss?
Click to expand...
4 hours should be plenty long enough to lose 1 ppm FC by organics. I probably wouldn't go less than 4 and certainly a little more would be better, but 4 hours should constitute a valid test.
 
Thanks for all the replies!

My CC level has been running 0 to 0.5.
I started SLAMing because I kept losing lots of chlorine overnight to the point where I was running at 0 FC for a few days. I've purchased and been using the TF-100 kit that you guys reccomend.
The condition of the pool itself has never been below slightly cloudy.

I actually miscounted, today is going to be day #7 of SLAMing.

With regards to the stuff floating in the pool, I've been trying my best to keep it clear of debris but its difficult due to windy weather blowing pines and such into the pool.

I do notice a thin black layer on the bottom of the pool that seems to come back despite brushing and vacuuming it away every day. It usually returns by that same night. Could that be black algae?
 

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You need to add your pool equipment in your signature so the experts can help you solve your issues. Your location-region, state, etc. helps as well.
Go to User Control Panel (upper left) select Profile, then Edit Signature :wink:


Check your ladder or remove it from the pool if you can. Remove any "floating things" from your pool, these areas are a breaking ground for algae.
Click to expand...
If you have any lights, (turn off power/breaker) remove light from niche and brush/clean it out. Expose it to the SLAM process.
 
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