Identifying and solving algae problem

[Remington]

I am 3+ days into SLAM but have a persistent algae problem (attached photo). The alleged algae shows up in same spot every day (also in the corner of the deep end). It brushes like a fine dust but returns the next day. Brushing daily and running Z5 2-4 times a day. Slammed at mustard level+++ for 24 hrs (39 is MA slam level per calculator). Filtering (sand) 24/7 and maintaining pressure within range. 3-4 chlorine adjustments/per day. Water is otherwise very clear and had decent chemistry before starting SLAM. TF-100 test kit. 25,000g vinyl liner. Uncovered and good sun during day. Autocover at night.

Please help identifying algae (usually makes appearance most overnight) but also a little during day between vacuuming and thoughts on how long SLAM will take to solve. Thought I was making progress on day 2 but OCLT dropped a ton on day 3.

Pre-SLAM chemistry:
ph 7.6
FCL 4
CC: 0.5
Alka 235
CH 202
CYA 70

day 1 SLAM FCL 34
day 1 OCLT FCL 23.5 CC 0.5
day 2 SLAM FCL 44
day 2 OCLT FLC 39 CC 0.5
day 3 SLAM 31
day 3 OCLT 23 CC 0

 

[Azgirl71]

Have you tried sneaking up on it using a manual vacuume? Brushing helps, but if it is heavy enough it will just sink back tithe bottom. I assume you have filter running 24/7, correct?

- - - Updated - - -

As for how long to SLAM you do it until you pass all criteria of the SLAM.

 

[duraleigh]

Three days is not Long for a SLAM and actually is pretty normal.

I am a little bit curious why your FC levels are so varied? Why do you think you have mustard algae?

My suggestion would be to peg your FC at 28 ppm per the chart and calculate your dosages a little more carefully.

Dosing twice-three times daily at your stage is frequent enough.

You are close to finished. Replenish your FC to 28 each time you test and continue to vacuum and brush as often as you see debris in the pool

All in all, you are doing a nice job and your pool is not too far away from really sparkling.

 

[Remington]

Thanks. I'll run the manual VAC today and keep shock levels closer to 28.

As I understand it, swimmers can swim safely at shock level, correct?

 

[Azgirl71]

You can have swimmers below SLAM level. Don't wear good suits though.