Algae appeared with FC maintained at 6+???

[Lrooth]

We have had 50 degree weather for a week, so I haven't taken the cover off until today. I have spots of green algae growing on the pool flow in spite of maintaining a 5 plus FC LEVEL. Tested every other day and added bleach or cal hypo to keep on the high side of normal. I will begin a slam, but I'm curious as to WHY Algae would grow at a 5 plus FC level.

TODAYS READING (close to this all week)
FC 7.0
CC 0
CYA 35
PH 7.2
TA 130
CH 210
Temp 80

Pool calculator says to add 2lbs cal hypo to get to recommended shock level. Out of bleach.... Cal hypo is my back up of choice.


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[Texas Splash]

Hello Lucy. Can you confirm which test set you are using please? Well, as a TFP member you can expect we'll all be saying for you to get some bleach right? At first-glance, your numbers look pretty good. Perhaps the pool cover kept your water temperature a little higher than normal ambient temps resulting in the suspected algae outbreak. In either case, if you have algae, you probably know the drill ... follow SLAM (link below). Happens to us all for one reason or another. Good thing is that if your CYA really is only 35, your shock level is only about 16 for non-SWG. Do you use a SWG? I didn't notice it in your sig. The chart links are in my sig if it helps.

 

[Richard320]

I'd guess poor circulation is the problem.

You test adequate FC yet obviously there wasn't or you wouldn't have algae. Which means what you tested and what really was where the algae formed are not equal.

The solution is a SLAM and lots of brushing. The long term solution is try to aim your returns so you don;t have any dead zones and to brush more often in the future to keep chlorinated water moving through those dead areas.

 

[Lrooth]

Thank you. I use a K2006 test kit. Yes, circulation issues are probably the culprit. My pool is 55 years old or more.... I don't have adjustable returns. I haven't put in the screw in floor diverters, which are located on the shallow end floor. That's where most of the algae patches appeared. I did brush this morning. No algae is showing now. I will continue with slam.

I also think my pool paint chalking might create a place for algae to thrive. Every time I brush, the "15 year guarantee" "Poly One ****" pool paint creates clouds of powder that the DE filter ultimately removes. Looking to do another paint job next year.

As always, Thanks for feedback.

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