Hello, been using the TFP method since April of this year after I fired the pool guy. These forums have been a wealth of information and everything has been going by the book until recently.
In the end of June I noticed small yellow patches in the attached spa and a few in the shady areas of the pool. Fearing I had the dreaded mustard algae I did the mustard algae slam and everything went according to plan. Four days later by the beginning of July I could no longer see the yellow patches in the pool, but there were slight yellow streaks in the spa. These "streaks" would not brush off no matter how vigorously I worked at them, so I thought they were stains. My numbers were fine (4FC, 0CC, 7.8PH, 100TA, 70CYA) for 3 days so I thought I was fine. Set my SWCG at 60%-8 hours/day and went away for a 4 day vacation.
Came back to 0FC and yellow patches all over the pool and spa!
Started a Slam again on 7/12 - starting numbers: 0FC, 7.4PH, 100TA, 70cya. Turned on the filter for 24/7 and turned off the SWG, using the PoolCalc and a FAS/DPD tester I brought the FC level up to 39. First OCL was 18ppm.
7/15 - I brought the FC level up to 45, OCL was 17ppm.
7/16 - I brought the FC level up to 45, OCL was 8ppm.
First question, am I supposed to keep the FC level at Mustard Shock levels or let them fall to regular SLAM levels (and then do OCLT)??? Since I am still having OCL, there must still be algae present, right? Any advice at what my next course of action should be?
Some notes: Because of my job, I can only check the water/add chlorine at 6:00am (before I leave for work) and after 5:00pm (when I get home). Current Southern CA weather is mid 80s and no clouds - my pool is in the sun from 8:00am to 7:00pm. My water is super clear and has been throughout, but I have been brushing daily and vacuumed before slam.