Chlorine Makes Pool Cloudy Temporarily

Jun 30, 2015
49
Washington/DC
Pool Size
28000
Surface
Plaster
Chlorine
Liquid Chlorine
When I add liquid chlorine (Pool Essentials 10%) to the pool it clouds up as it spreads away from the return jet. Picture attached. The cloud ultimately dissapates within an hour, but I had never experienced this. Does not matter if I am adding a third gallon, half gallon or full gallon and does not matter how slow or fast I pour. I test chlorine and Ph and daily to aim to keep at 5 and 7.5 respectively and full workup weekly. Here are results from Sunday:

Ph = 7.5
FC = 5
TA = 100
CA = 225
CYA = 30

By way of background, pool remodel was completed in the spring, including DiamondBrite Bahama Breeze exposed aggregate plaster.

Theory 1 - Contractor initially had TA up to 140 and I've slowly brought that down as I've managed the Ph bounce. Initially I thought it was the high TA as historically I've found 70-90 to be a sweet spot for my pool, but even as the TA has come down, the "chlorine cloud" still appears.

Theory 2 - The only other thing I know that was added to the pool was Jack's Blue Stuff. I'm not sure why they added this as the pool was filled with municpal water which does not have above normal metals in in. There was one other thread I found on here (Adding chlorine makes water cloudy), for which a metal sequesterant appeared to be the culprit, but didn't seem to have a definitive answer. Regardless, following numerous backwashes since that was added in early May I would think that the sequesterant would be out of the water (my daily chlorine loss is well within normal range so it is not being consumed by sequesterant), though admittedly, I do not have a sequesterant test kit and have not tested.

Theory 3 - The last thing I could think of is that maybe with the darker pool surface, this cloud is just normal, especially given it disappates quickly.

My questions - What could be causing this and is there a way to stop it? Do I even need to do something to stop it as I seem to have a perfectly balanced, clear swimming pool with no issues this summer beyond this?
 

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I test chlorine and Ph and daily to aim to keep at 5 and 7.5
If you lose 3 or 4 ppm a day to the sun, how do you keep it at 5 ?

Do you dose to 5, or dose above and fall to 5 ? Either way, it's not keeping it at 5. :)

Also either way, Overnight Chlorine Loss Test. You're probably sitting on the fence of a full blown swamp outbreak.
 
If you lose 3 or 4 ppm a day to the sun, how do you keep it at 5 ?

Do you dose to 5, or dose above and fall to 5 ? Either way, it's not keeping it at 5. :)

Also either way, Overnight Chlorine Loss Test. You're probably sitting on the fence of a full blown swamp outbreak.
Agree it is not keeping at 5. I dose to 5ppm. I generally burn 1-2ppm per day and add between a third and half gallon a day.
Not sure the basis for the "full blown swamp outbreak" comment. CC=0 and no overnight chlorine loss.
 
no overnight chlorine loss.
So you've done the test officially ?
Not sure the basis for the "full blown swamp outbreak"
Adding chlorine and immediately going cloudy is most likely because the FC was too low and the new addition gets right to work killing the algae that was starting to fester.

It's microscopic and you can't see it until it's way too late. It grows exponentially so time is of the essence to nip it in the bud when present. That's where the OCLT comes in.
 
What they said. 👍

It doesn’t take much at all to start the algae problem. Unless you are committed to keeping an eye on your chemistry non-stop you’re flirting with disaster keeping the FC levels on the low end.
 
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Just had this with a new clients pool. As soon as I reached slam level it looked like a chemical reaction for the first day as I have no idea what the previous pool guy did. Eventually keeping at slam level made the reaction less...
 
Post a full set of current test results to PoolMath.
The last results there are over 2 years old.

Do the Overnight Chlorine Loss Test
Chances are you have a nascent algae bloom - which is about ready to get worse.

What test kit are you using? How old are the reagents?
Add your test kit to your signature.
Those full results are from 4 days ago. Ph and FC are from yesterday. Testing done with TF-100 and reagents all purchased new this spring.

Not buying the algae as I have been on top of the chemistry every day since the pool was filled. Doesn’t make sense to me. Couple with the fact my daily chlorine burn is well within normal range.
 
What they said. 👍

It doesn’t take much at all to start the algae problem. Unless you are committed to keeping an eye on your chemistry non-stop you’re flirting with disaster keeping the FC levels on the low end.
I do test daily. That’s what I’m confused about. And how is 5ppm for 30 CYA level on the low end? It’s smack in the middle of the recommended level.
 

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So you've done the test officially ?

Adding chlorine and immediately going cloudy is most likely because the FC was too low and the new addition gets right to work killing the algae that was starting to fester.

It's microscopic and you can't see it until it's way too late. It grows exponentially so time is of the essence to nip it in the bud when present. That's where the OCLT comes in.
I understand this. Before I found TFP I was intimately familiar with algae blooms. And ever since finding the way I can specifically blame broken equipment or neglect / vacation for algae problems. I’ve never been more on top of my water chemistry and pool care the way I have been this season since effectively getting a brand new pool.

It’s been a couple weeks since I did a OCLT as I have had no reason to do one (like I said my daily chlorine loss is well within normal range) but to rule out I will do one tonight.
 
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When you are recording your 5 FC, is that before or after adding your chlorine?

If you are dosing your chlorine to 5, then that's low as it will drift down and you likely are at/below the minimum by the time you add chlorine again.

If you are testing 5, then adding chlorine to get to 7-10 so that it stays in the target range... that's the right approach, but some pools need a higher FC target range for whatever reason. No harm in joining team #runhot, just look at my avatar and see where I keep my chlorine :)

Either way, your pool is telling you it needs more chlorine so listen to it.
 
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you are dosing your chlorine to 5, then that's low as it will drift down and you likely are at/below the minimum by the time you add chlorine again.
*somewhere in the pool.

Everyone always forgets they only tested a small cups worth of a much, much larger container. Sure it mixes pretty well but not perfectly or not perfectly everywhere with dead zones.
 
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Team - let me clarify. I follow these guidelines

For my CYA level min is 2ppm and target is 4-6ppm. I test nightly BEFORE adding chlorine. I have NEVER been below 2.5 and am typically at 3.5ppm. I then add 10% liquid chlorine to target 5ppm. It seems like several are suggesting to put more chlorine in than the guidelines of this forum. That’s fine if that is the answer, but it doesn’t make sense to me in the 8+ years I’ve been following this forum and methods.

Regardless, I’m doing OCLT tonight an will report back tomorrow.

Tonight’s result AFTER adding chlorine is 6ppm. Will test again tomorrow morning before adding muriatic acid (Ph tonight is 7.8).
 
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Did the contractor add any scale and or stain inhibitor? I’ve seen this when those products are added (often times in a winter closing kit) into elevated chlorine levels.
 

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