having possible mustard algae problem 3 weeks now

[bluebayou]

you had me to do the DE test and none came out the returns.

Sunday afternoon I added 3 pounds of 53% cal hypo and 3 cal hypo tablets to the skimmers.
Monday the FC was 10 ppm.

I intentionally did not do anything the pool yesterday. As of right now, 24 hours later, the FC is 5 ppm.
I have new growth on the shady sides and in the deep end. The brown powder is accumulated on the pool floor, but does not have new growth under it.

I think that the powder is dead algae being returned into the pool.

My question is: where is the LIVE algae? if there was active growth some place in the plumbing or filter then would that explain it? I would figure that algae needed sunlight. We do not have lights in the pool. The skimmers could use a cleaning, but no algae visible there.

If I had to estimate then I would say there is one square foot of visible green algae growth TOTAL in the pool right now. But, I have maybe 5-6 square feet of the brown powder at a time.

Would the drop from 10 ppm on Monday to 5 ppm today be normal? Seems too fast to lose that much chlorine with CYA at 75

[PoolDoc]

When mustard algae is breeding, you will lose chlorine faster than normal.

1. Operate your filter 24/7.
2. Keep your chlorine in the ORANGE to orange-tinted DARK YELLOW range.
3. Add 2 - 3 cups of DE powder after EACH backwash. That will stop algae from leaking through.
4. Brush the algae spots after each chlorine boost.

Where did you get 53% cal hypo? What *else* is in it? What's the brand/product name?