If FC good can you still get algae?

nksprts

Silver Supporter
Aug 10, 2016
197
NE Pennsylvania
Hi all, super disappointed. All year I have been bragging to my wife how amazingly clear I have kept the water. I downloaded the pool math app and have upgraded to paying for all the features. I have been logging daily. Everything has been going great! Then today.... It was getting dark after I cut the grass so couldn't investigate to much. Anyway the entire season so far my water has been perfect. Besides adding the inial cya, I've had to add nothing other then chlorine. Test daily and has been great and easy with the app.
My last full readings are attached. Been great all year. Now granted last 2 weeks have sucked here, cold and rainy. But still have been checking and adding chlorine as needed. I was out of town yesterday but Friday pool was still crystal clear and everything good. And Friday I gave it an extra ppm since I knew I wouldn't get to it. So check the pool today as it's getting dark and FC is 6.5. Friday had it at 8.5.think everything is fine and notice algae on the bottom. Just in the one side as well. My FC as never dropped below 5 all season. Can you still get algae even though your chlorine had maintained? Is there something I missed or didn't do? Is my pump not circulating the chlorine enough to that side? Well as I said it was getting dark so took scrubbed the areas real quick to get the algae up and pumped it up to 10. (thinking algae will eat it up) but still don't understand I am only losing 1 or max 2 ppm a day and that is real hot days or rainy days.... What am I missing? Do I have to slam? Figures been great and now this when me and the wife are on staycation next week.


Thank you for the help.
 

woodyp

Mod Squad
TFP Expert
LifeTime Supporter
Apr 17, 2010
11,129
East Texas
Awful hard with those numbers, but you know what they say...some times bad things happen to good people.
 
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JJ_Tex

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Jul 17, 2019
2,294
Prosper, TX (DFW)
Pool Size
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That sucks, usually people are mis-reading the chart but you are not even close to the minimum. How confident are you on your CYA of 30?

Are you sure it is algae? I would take it up to slam level (12, not 10) and do an OCLT just to see how much you lose overnight.
 

nksprts

Silver Supporter
Aug 10, 2016
197
NE Pennsylvania
I will say I was not super strict with the kids brushing the pool this year.... Would that be it then? Ughhhh, so disappointed in myself. Do I still need to slam or since my FC never dropped to danger levels do I just need to brush and maybe it will clean itself up?
 

nksprts

Silver Supporter
Aug 10, 2016
197
NE Pennsylvania
Pretty confident. I actually think it would of been about 35 but I read read down. And I do everything weekly and FC daily. Thought I finally had this down to science..... 😢
 

nksprts

Silver Supporter
Aug 10, 2016
197
NE Pennsylvania
And pretty sure algae... It's been a few years but greenish spots at bottom when brushed it sweeps up like dust almost and starts turning water cloudy.
 

Mike1162

Silver Supporter
Jun 13, 2015
722
N Tonawanda, NY
Give it a good brushing tomorrow & you'll probably be fine. If you see more algae in a few days then do a SLAM. If you don't want to take any chances then do an OCLT today or tomorrow.
 
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Costas > DownUnder

Bronze Supporter
Dec 17, 2017
665
Adelaide | Australia
Circulation plays an important part.

In some instances you may experience algae growth even with good measured FC levels as the FC level may not be even throughout the whole volume of water in the pool.

In areas of poor circulation it could drop below acceptable levels during certain times of the day.
 

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revitup

Gold Supporter
Bronze Supporter
Nov 30, 2019
415
Pawleys Island, SC
Pool Size
8500
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Circulation plays an important part.

In some instances you may experience algae growth even with good measured FC levels as the FC level may not be even throughout the whole volume of water in the pool.

In areas of poor circulation it could drop below acceptable levels during certain times of the day.
Really? I was under the impression that if any chemical disperses evenly throughout the pool with minimal pump action, it was chlorine. How does liquid chlorine collect in some areas and not in others?
 

Mdragger88

Bronze Supporter
Jun 1, 2018
1,773
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
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Intex Krystal Clear
Have u checked the seams/flaps? When i had one of those pools that was an issue for me. The flap of the seam wasn’t able to get flow so it required frequent brushing or else it would allow aglae to grow even in properly chlorinated water. Some of the intex pools have “flaps” in the seams & some don’t - its a manufacturing issue.
also if u switch on sharing in poolmath we can see all your logs & may be able to identify an issue.
19A18DB4-E91F-4D28-AAF1-FC0468CBCBD9.png
 
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Dtkokay

Well-known member
Dec 31, 2019
379
Houston, Texas
Really? I was under the impression that if any chemical disperses evenly throughout the pool with minimal pump action, it was chlorine. How does liquid chlorine collect in some areas and not in others?

I've lived this first hand. When my pool was new, I always measure in the middle assuming the numbers would be consistent throughout the pool. Wrong. One day I decided to measure FC at each end of the pool and the middle, and I found a 2 ppm difference. FC was highest at the end closes to my pool equipment and lowest at the farthest end.

As a result, I put a more restrictive return nozzle nearest my pool equipment and reoriented some of the other nozzles. Now I get a pretty consistent reading across the pool.

I suggest you take several different readings around your pool to confirm consistent numbers, and take the water sample at least a foot under water. Hopefully you get the same results everywhere, but regardless it's a good sanity check.
 
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ping

TFP Expert
LifeTime Supporter
Jun 24, 2011
3,143
Long Beach, CA
Do you have a ladder in the pool? Ladders can be a source where algae loves to hide and proper chlorine levels might not be enough if the ladder is not cleaned often enough.

Have you been brushing weekly? If not start brushing.

I would bring the FC up to SLAM level for 40 CYA since it is above 30 and run an OCLT tonight.
 

nksprts

Silver Supporter
Aug 10, 2016
197
NE Pennsylvania
Thank you

I turned on sharing.

No there is no ladder. Since it's not fenced I pull it out and lock in the shed when not in use.

Good news it didn't look like a lot reformed over night just some sports still thee einciukdnt get to because I didn't want to get in. Getting in now and giving it a good scrubbing. We'll do a oclt test tonight?
 

nksprts

Silver Supporter
Aug 10, 2016
197
NE Pennsylvania
I just scrubbed and and skimmed everything. I reran a week's tests and have attached the results. Looks like I lost about 3 ppm of fc since last night 830 pm. As I said no new noticeable algae or anything like that. Not crystal clear but could see to the bottom. Thoughts on next steps or just monitor?
 

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Mdragger88

Bronze Supporter
Jun 1, 2018
1,773
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
I would do as @ping stated especially since you have seen visible algae & you stated its not crystal clear.
Sometimes the higher level Overnight Chlorine Loss Test
Can really show u the truth. Or u can just omit the oclt & begin slam now. Hopefully it won’t take too terribly long as maybe u have caught it early.
 
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nksprts

Silver Supporter
Aug 10, 2016
197
NE Pennsylvania
Well it got dark on me and didn't get to go back out (don't have lights) I gave it a good scrubbing and skimming and added my nr9mal amount right at dusk. So I essentially did a oclt test... As it was getting dark I was at 8.5 ppm of fc. I tested this morning about 9:30am and was still at 8.5 ppm... So I had 0 loss over night. Which that is a good thing isn't it? Do I just keep giving it a free brushes and keeping eye on chlorine? Or still slam even though I passed the oclt test.
 

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