Why would pool be growing algae if my numbers are correct?

Skenn81

Well-known member
Apr 23, 2018
145
Florida
The main numbers anyway.. using the chart: https://www.troublefreepool.com/blog/2019/01/18/chlorine-cya-chart/

CL is kept at 8 every couple of days with me tesing and adding liquid, I have not had it drop below 6 on my tests - at least recently. For a while CYA was between 30 and 40 - it would be 3 when I would check it every 3 days and I would bring it back up to 8.
CYA is at 50
pH is kept around 7.6 to 7.8

On the bottom of the pool there is a growing fine mist of green, when you rub your hand over it or take the broom to sweep you can see it billow up.

I can still see a coin at the bottom when dropped into the deep end but I know something is wrong.

Pump has been upped now to running from 7am to 10am on high speed, 10 to noon on a lower speed.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,925
San Dimas, CA (LA County)
Algae grows a protective film that shields it from chlorine. It's needs to be broken up by brushing so the chlorine can get at the algae and kill it.

Now that you have algae, you need the SLAM Process which includes a lot of brushing and vacuuming. After it's complete, you'll need to keep brushing regularly. Or buy a creepy crawly or a robot or something to do it for you.
 

Skenn81

Well-known member
Apr 23, 2018
145
Florida
I SLAMed last year when things went totally wrong and things have been looking great, until these past two weeks. Took a few days but then the pool was great again, until now.

I have a Polaris that crawls around for 3 hours a day so I never really brush myself too often.

What causes this to start? I like to think I go out there often enough, multiple times a week, to check and raise the CL levels to prevent this from happening, but was it not enough? I figured if I kept the levels in range and brought them back up every few days it should be okay.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,641
Laughlin, NV
When using liquid chlorine, daily additions are really needed during warm water / swim season. Some get away with every other day, but that is mostly in the north with lower UV load. Is this pool in a screened enclosure?
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
18,847
Bedford, TX
81,

My guess is that you never got rid of all of it to begin with... You got most of it during your SLAM..

Algae can hid behind the light and under ladders, etc.. Brushing when doing a SLAM is really important.

Once you get algae, the target FC level will just slow it down, but it won't get rid of it.

Thanks,

Jim R.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,925
San Dimas, CA (LA County)
I SLAMed last year when things went totally wrong and things have been looking great, until these past two weeks. Took a few days but then the pool was great again, until now.

I have a Polaris that crawls around for 3 hours a day so I never really brush myself too often.

What causes this to start? I like to think I go out there often enough, multiple times a week, to check and raise the CL levels to prevent this from happening, but was it not enough? I figured if I kept the levels in range and brought them back up every few days it should be okay.
Does that Polaris have brushes or is it just a vacuum?
 

Skenn81

Well-known member
Apr 23, 2018
145
Florida
Last years SLAM was a very intense process, I went behind the light and everywhere else. The pool was so green you couldn't even see the bottom of the shallow end.

This time we can still see the bottom so it was caught early. SLAM started, pool CL jacked up to 20, will be making a trip to the store later to reload all of the CL jugs and we'll see where we end up in a few days.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,998
Franklin, NC
Something isn't working out. A pool with 30 - 40 CYA exposed to the sun in Florida will have more chlorine loss than 1ppm per day. The average we see nationwide is a loss of 2 - 3 ppm per day and yours should be at the higher end of that loss.

What are you using for testing the chlorine?
 
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Skenn81

Well-known member
Apr 23, 2018
145
Florida
That was a puck emergency during quarantine. Ended up using 5 total over the past three months when I wasnt leaving the house. Back to normal now. Other than that it's just been liquid.

I use a Taylor test kit k-2006 and replace the reagents when they expire.

For brushing, no, I have never done that except when things go wrong, I always thought thats what the Polaris did by sucking things up. With it being enclosed by a screen nothing ever gets into it so I don't pay much attention other that checking the levels a few times a week. When I keep up with logging my results I usually lose 1.5 to 2 a day of ppm.
 
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borjis

LifeTime Supporter
Aug 19, 2014
3,286
Pacific NW
Brushing daily during a slam, better yet twice daily, is super important to the process. You have to break the biofilm so the chlorine can get to it. It's not any kind of fun, but very necessary.
 
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Skenn81

Well-known member
Apr 23, 2018
145
Florida
With all the people who have pool guys who only come a few times a week how do they maintain clear pools if they are not having chemicals added on a daily basis?
 

JW1

Well-known member
Sep 4, 2019
163
SW Ohio
Last years SLAM was a very intense process, I went behind the light and everywhere else. The pool was so green you couldn't even see the bottom of the shallow end.

This time we can still see the bottom so it was caught early. SLAM started, pool CL jacked up to 20, will be making a trip to the store later to reload all of the CL jugs and we'll see where we end up in a few days.
Just curious....when slamming are you suppose to add all your slam LC to just one return or divide it up?