Overnight Chlorine good but get some algae

Haggises

Member
May 31, 2021
12
Merion Station, PA
Pool Size
8600
Surface
Vinyl
Chlorine
Liquid Chlorine
Hi all,
Have noticed a couple of spots of algae on my Intex 24x12 over the last couple of weeks. Easily vacuums off, patches never more than 2" across.
I've been keep the chlorine at 4-5ppm each day after I test but the algae was worrying, so last night did my first overnight Chlorine test - 3.4 last night, 3.4 this morning.
That would seem to indicate no fundamental algae problem.
Thoughts welcome. (yes I know my CYA is a little low :))
 

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Newdude

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TFP Guide
Jun 16, 2019
11,558
NY
Hey Haggises and belated Welcome !!

Bad news : Algae is algae. If you see it you have it. There are no two ways about it. To rid it you need to SLAM Process

Good news : If it’s not a huge bloom, it will be a much easier SLAM. Sometimes only a day or two for folks.

A little of both news : Everything could be fine and it could be a dead spot with poor circulation accumulating the algae while you do everything right. Adjust the returns a little to try and get better flow in the general area while still pushing towards you skimmer.

In the interest of being thorough, I want to go over the OCLT. There are some simple goofs that can skew the test for false positives. If nothing applies then at least we made sure. :)

1). Pool well mixed before both tests
2). Time taken to squeeze gently allowing gravity to form repeatable drops. (Be hasty in the evening and get a lower than actual reading, making it look like it passes in the AM).
3). Test bottle completely upside down, also for gravity / repeatability

Also, switch to 10ml samples and each drop is .5 FC. It will save a bunch of reagents and be plenty close enough.

Also also. When was your filter last backwashed / deep cleaned. It could be residuals being blown into the pool.

Also also also. Lol. Fill out your signature with all your details and equipment. It helps us not ask you more questions like what kind of filter you have and/or which one specifically (size/brand)
 

cowboycasey

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LifeTime Supporter
TFP Guide
Jul 3, 2013
8,648
Southern OK
Pool Size
15000
Surface
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Chlorine
Salt Water Generator
SWG Type
CircuPool SJ-40
Your CYA is perfect, you can go to 40 if you want, it may also help with what is going on... I would raise your daily FC to 6 and see what that does, sometimes pool with a little less circulation require a little more FC.. You could also take your FC to SLAM Process for a day and let it drift back down just to make sure if something was trying to grow it wont :)
 
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Haggises

Member
May 31, 2021
12
Merion Station, PA
Pool Size
8600
Surface
Vinyl
Chlorine
Liquid Chlorine
Hey Haggises and belated Welcome !!

Bad news : Algae is algae. If you see it you have it. There are no two ways about it. To rid it you need to SLAM Process

Good news : If it’s not a huge bloom, it will be a much easier SLAM. Sometimes only a day or two for folks.

A little of both news : Everything could be fine and it could be a dead spot with poor circulation accumulating the algae while you do everything right. Adjust the returns a little to try and get better flow in the general area while still pushing towards you skimmer.

In the interest of being thorough, I want to go over the OCLT. There are some simple goofs that can skew the test for false positives. If nothing applies then at least we made sure. :)

1). Pool well mixed before both tests
2). Time taken to squeeze gently allowing gravity to form repeatable drops. (Be hasty in the evening and get a lower than actual reading, making it look like it passes in the AM).
3). Test bottle completely upside down, also for gravity / repeatability

Also, switch to 10ml samples and each drop is .5 FC. It will save a bunch of reagents and be plenty close enough.

Also also. When was your filter last backwashed / deep cleaned. It could be residuals being blown into the pool.

Also also also. Lol. Fill out your signature with all your details and equipment. It helps us not ask you more questions like what kind of filter you have and/or which one specifically (size/brand)
Thanks for the detail response!
Circulation - I could try moving the skimmer port over one but that's about it with my intex.
Slam - may try this weekend, or just bump up my dosage to 6-7 for a couple of days

Testing - all duly noted!

Backwash - weekly, but yesterday the pump was at 9 psi instead of usual 4 before I backwashed it, so I'll go biweekly to see if it helps.

Signature - done!
 
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Haggises

Member
May 31, 2021
12
Merion Station, PA
Pool Size
8600
Surface
Vinyl
Chlorine
Liquid Chlorine
Your CYA is perfect, you can go to 40 if you want, it may also help with what is going on... I would raise your daily FC to 6 and see what that does, sometimes pool with a little less circulation require a little more FC.. You could also take your FC to SLAM Process for a day and let it drift back down just to make sure if something was trying to grow it wont :)
Thank you! I'll take it to the 6-7 ppm range for a couple of days.
I'll leave CYA as is for now as Im going on vacation in a couple of weeks and will load up with 3 3" tablets while I'm gone and hope for no power outages that trip the GCFI to keep the pump on schedule.
 

JJ_Tex

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Jul 17, 2019
2,539
Prosper, TX (DFW)
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Thank you! I'll take it to the 6-7 ppm range for a couple of days.
6-7 is really not that high for your CYA.

Take a look at the FC/CYA chart. For a CYA of 40, your pool should spend the majority of the day in the target range of 5-7. That means dose to 7-8 on a algae free day and let it drift down.

Since you noticed some algae, the best answer is to SLAM, but if you do not want to right now, take it up to 8-9 on a daily basis with liquid chlorine for a few days and see what that does.
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
1,015
Verona, MO
Backwash when have 25% rise in pressure instead of time frame. Depends on how much filtered out. Pool filters are like air/oil filters for cars, work better after pick up a bit of stuff. Too clean and don’t pick up as much.
 
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Haggises

Member
May 31, 2021
12
Merion Station, PA
Pool Size
8600
Surface
Vinyl
Chlorine
Liquid Chlorine
So, number one rule of this forum - if you ask for advice, take it! Along with the other Golden rule, if in doubt, SLAM.

Wednesday I raised CL to 8ppm, Thursday I chucked in a cup of 12.5% without measuring. Friday, I measured at 6.5 and thought close enough. Saturday, came to a pool with green floor and walls.

I vacuum/brushed every square inch, changed skimmer sock, took all accouterments out of the pool and wiped them all down, raised chlorine to 12 ppm and will keep a close eye on it. I don't have time to do SLAM process in detail today but will check chlorine later and go full process tomorrow.

I suspect that, along with my haphazard approach, putting the solar blanket back on after it had been sitting on a chair for a week contributed to the algal growth.

Several lessons learned I think.
Thanks for the advice all, this time I'll listen :)
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,558
NY
So, number one rule of this forum - if you ask for advice, take it! Along with the other Golden rule, if in doubt, SLAM.
Excellent. But you left out the holy grail. The gospel of the FC/CYA Chart. Never go below minimum. Never fall to minimum. Never even *THINK* of falling to minimum. Ever.

Do this and we will never discuss your algae again. (y)
 
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Haggises

Member
May 31, 2021
12
Merion Station, PA
Pool Size
8600
Surface
Vinyl
Chlorine
Liquid Chlorine
10 ppm this morning, brought back to 12.
9.5 this afternoon and same. Extensive brushing and vacuuming, amazing how much more you can see from inside the pool with goggles on.
Unfortunately, in the ER now with suspected appendicitis for daughter, so pool schmool.
 

Haggises

Member
May 31, 2021
12
Merion Station, PA
Pool Size
8600
Surface
Vinyl
Chlorine
Liquid Chlorine
The good news is that the appendectomy was a success and now have her home recuperating.

24 hours away from the pool and Chlorine was 8 ppm, 7.6 pH and algae in evidence. Not as bad as last week but not nice.

Added dry acid to take the pH down a peg or two. Rechecked CYA and it looks like it's between 30 and 40 now, so calling it 40 and took the Chlorine to 16ppm.
Will vacuum and brush the Crud out of it tomorrow.
 
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Haggises

Member
May 31, 2021
12
Merion Station, PA
Pool Size
8600
Surface
Vinyl
Chlorine
Liquid Chlorine
Got some reoccurring algae because I didn't have time to do the M in Slam. Seems all good now just as I go on a 5 day vacation....
Trichlor tabs and starting FC at 16 should maintain me while I'm away, fingers crossed.
 
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