Algae Despite High Chlorine

[magnetar68]

Hi All,

14000G plaster in ground pool. Intelliflow VS pump runs at 2100RPM from 8am to 9pm. Cartridge filter. Use TF100 (new test kit as of July).

Went away on vacation and pool sitter let it get a little green. I SLAMed the pool two weeks ago when I got back and things were fine, but this week noticed a little green on the side in the corner. Chemistry is good:

FC 7 (I have been keeping this a little high since the SLAM)
TA 100
CYA 40
Calcium 300
ph 7.5 (there is about average, but this is where it was this morning)
Temp 80F

Maybe I need to clean the filter better? Seems strange to get algae with the chlorine level above 7.

 

[YippeeSkippy]

You need to perform an OCLT (Overnight Chlorine Loss Test) to determine if there is anything organic in the water eating up your chlorine.

Instructions for OCLT---> Pool School - Perform the Overnight FC Loss Test (OCLT)

 

[Texas Splash]

I agree with YS. And since we don't have the details of the previous SLAM (test readings, duration, validation of all 3 criteria passing, etc) it's difficult to know if ALL the algae was actually neutralized a couple weeks ago. If not, if there was ANYTHING remaining, that's how it came back. The OCLT will confirm if you have algae now, and if you do need to SLAM, just make sure you follow the Pool School - SLAM - Shock Level And Maintain to the letter. After that, "then" maintaining your target will be just fine. Remember:

When performing the OLCT, remember that it must be done when the sun has dropped – no sunlight on the pool. About 8 hours total is recommended. Also, your FC level should be elevated more than normal. Starting (bedtime) FC could be close to your SLAM level, but no lower than 10. Anything less and you may not receive an accurate portrayal of FC loss (by percentage), even if it’s only 1 ppm.

Best of luck to you!

 

[PAGirl]

Is it in an area that could have poor circulation? Do you brush the pool regularly?

 

[pabeader]

I'm with PA on this one as to cause, sounds like circulation trouble in that corner.

Repair is the same as always, SLAMing time!!

Long term, is there a way to direct a return more into that corner?

 

[Divin Dave]

+1. PAGirl hit the nail on the head.

Corners are notorous for poor circulation and we should all brush our pools at least once a week. Even keeping our FC in check, if we dont have really good circulation and brush, its a likelyhood, that there will be minor bouts with algae sooner or later.

Is it in an area that could have poor circulation? Do you brush the pool regularly?

 

[magnetar68]

Thanks everyone! (a bit late on the response)

OK, so I get it. I probably did not quite get it all last time. And yes, places where there are poor circulation. I brush the pool here and there but not as regularly as I should. I will SLAM it again.