Do I actually have Mustard Algae?

[dreamweaver]

I have been seeing, what I believe to be mustard algae in my pool.
AGP Intex 22' x 54"....11400gal.
Hayward XStream Matrix Cart filter system: CCX1000
My extra test kits have come in and I have tested the crystal clear sparkling water....lol....it really is. I shocked late night according to my CYA
Last nights readings:
CYA: 100
FC: 39 (Shock level)
CC:0
TA: 70

Today's reading @ 2 pm. EST
FC: 29 (brought back up to 39ppm)
CC:0

If I do have mustard algae, why would my CC be @ "0". Doesn't the CC indicate pathogens ie. algae in the water .
When ever I shock the pool...bleach.... the yellow coloring goes away, and soon as the FC comes back down to normal then the next day I see it again. There is not as much yellow any more, but it's there.
I'm confused with the CC reading of "0"
Tonight I'm going to bring the pool up to mustard shock (need to add 2.5 gal) to see what happens. Now that I know my CYA, I have been keeping my FC @ 8ppm.
Any suggestions?

[PoolDoc]

Mustard algae, in the presence of high chlorine and sunlight, won't necessarily lead to combined chlorines.

The most common contributors to combined chlorine are all 'people goo' -- urine, lotion, skin oils, etc. Combined chlorine is the result of chlorine partially, but not completely, burning up (oxidizing) various organics and 'goo' in the water.

Mustard algae appears as a greenish-brown to yellowish-brown deposit, that brushes away readily and reappears overnight. For unknown reasons, some pools are much more prone to mustard algae than others. At one time, I was servicing 25 large (>100,000 gal) pools. I treated all those pools pretty much the same way, but had problems with mustard algae at only 2 - 3 of them. Whatever the cause, it persists through all treatment, scrubbing, etc. I still service one of those pools (200,000 gallons) and it ALWAYS tends to get mustard algae by mid-July. There are some patches we have to brush away in the morning. Over the 25 years I've been servicing that pool, it has been acid washed (3x), pressure washed (5x), painted with epoxy (2x) . . . and it always tends to get mustard algae by season end.

I can knock it back with very high chlorine levels, but it will reappear. It seems to be related to water temperature, but it will grow when it's cool, if the chlorine gets low.

The ONLY thing I've seen stop this is very low phosphates, and that's what I'm testing on this pool. Please note that simply adding phosphate remover does NOT help. Algae needs only a small amount of phosphates in order to thrive. So if you lower your pool's phosphates from 3 ppm (3,000 ppb) to 1 ppm, it will likely have no effect at all. Even lowering your phosphates to 0.3 ppm does not seem to be effective. Unless you lower the level to 125 ppb (0.125 ppm), using a PO4 remover is useless.

Also, a low phosphate levels does NOT kill algae; it simply makes it grow more slowly, and thus makes it more susceptible to chlorine.

[dreamweaver]

I went to the pool store in town to have them check my phosphates and all other readings. She forgot to do the phosphate test and had all ready dumped my pool water....lol....so she just gave me the test strips/vial (11 strips) from Natural Chemistry. I wanted to pay for it and she said no because the sales reps gave her two and she hardly ever test for phosphates....lol.... so that was very nice of her. She had my reagent R-0009 2oz for the same price I could get it on line, so I got that as I was very low on mine

I tested and the reading was 300.

Their wasn't any yellow in the pool today but
FC: 29ppm
CC: 2.5ppm
My grand daughters were here this evening so I forgot to put the chlorine level back up. I will have to do that tomorrow night

[dreamweaver]

I am happy to say, that the mustard algae is gone. I kept the slam for this up for 3 days and it's been a week and no sign of its return.... I'm a happy camper

[PoolDoc]

Great!