Florida Winter Algae?

[FlyAU98]

My pool has been pretty much algae free since I fired the pool guy and started the TFP method. I probably didn't brush it as often as I should, but it probably got brushed every 1.5 weeks through the summer, and that has continued through the winter.

The last few weeks I have started having algae (I assume) growing on the walls, worse on the South side than the north (pool is closely aligned with the long way east-west). It brushes away into a light greenish/brown cloud, which then clouds up the pool.

I'm in South Florida, with solar heat, so the pool stays in the very low 80s during the day, FC level is maintained within the recommended 4-6 with a CYA of 40-50. (That said, it was probably around 3.5 tonight when I added Cl, but tonight was an anomaly)

Tonight's Cl test (after adding about 18-20oz of 10.5% Cl and discovering it needed to be brushed):
FC=5
CC=0.5
pH= ~7.7

Last weeks full test (didn't have time for a full run tonight):
FC=7
CC=0 (CC has been 0 since 9/28 when it tested at 0.5 and it had been 0 for long before that)
pH=7.5
TA=90
CH=250

On January 6th, CYA was 40 (after 3 days of tablets while I was away). There has not been anything to raise CYA since January 4th.

 

[JasonLion]

I'm not sure how it got started, but that sure sounds like mustard algae. Mustard algae grows on the walls and prefers the shaded side of the pool. You should go read the article on fighting mustard algae.

 

[FlyAU98]

My wife rushed me out the door to dinner while I was prepping to add the chlorine to SLAM... so I just dumped in a 2.5gal jug of Cl instead of measuring out the ~2.1 gal Pool Math called for to get to 20.

Retested before bed...a few hours after the addition:
FC=28
CC=0.5

It still looks a little cloudy via the pool light, but I rarely run it, so I'm not 100% sure what it would look like if perfect.

Via a google image search on "mustard algae pool", this is the only image that came up that even resembles what I had, but the sample image algae is MUCH darker and I didn't have any visible on the steps (a path my pool cleaner took through it was clearly visible though):

Its dark out now and I brushed it before I thought to take a photo, so I don't have a picture of my problem.

 

[FlyAU98]

I forgot to mention...

We have a big tree (oak?) in the front yard that has been dropping leaves like mad lately, a fair amount has made it into the pool, requiring daily skimming. This leaf issue has probably been going on about the same amount of time as this potential algae problem.

 

[FlyAU98]

Morning Cl Test, sample taken 22 min after sunrise, under heavy cloud cover :
FC=25 (drop of 3ppm)
CC=0.5 (same)

 

[JasonLion]

Remember to brush the pool daily while at shock level, you should brush everywhere, but especially on the walls where the algae appeared.

 

[Wizard43]

This sounds very much like my problem, see http://www.troublefreepool.com/threads/87909-Yellow-Green-Dust. The material is over all of the sides and bottom including the built in steps with no noticeable lighter and heavier areas. I am in central Florida on the Gulf side. I have several large oaks but very few leaves get in the pool since the pool is screened.