Mustard Algae and Combined Chlorine

[Lonnybass]

My pool has what appears to be traces of recurring mustard algae along the stairs and some of the shade areas of the walls.

Brushing seems to help significantly, but the yellow does reappear.

Is it possible to have mustard algae and still have a combined chlorine result of zero? (From time to time, it tests at .5).

Please let me know your thoughts. Here are my latest test results.

FC 5
CC 0
pH 7.4
TA 80
CH 200
CYA 40

 

[mknauss]

You can have algae and a zero CC.

If you have algae, you need to SLAM Process.

 

[Lonnybass]

Thank you my friend. SLAM commencing.

 

[Lonnybass]

Morning test result showed an overnight chlorine loss of 2 ppm (from 19 to 17 ppm).

Combined chlorine is zero.

Water is clear.

It appears I should be maintaining the SLAM until the overnight chlorine loss number comes down to 1.

 

[mknauss]

Maintain the SLAM until you pass all three criteria as described in the SLAM Process article.

Then, IF, you have mustard algae, raise your FC to mustard algae SLAM level for 24 hours. And then maintain a higher FC for a period of time.

Read Pool School - Mustard Algae

 

[Lonnybass]

Thanks!

2/3 criteria complete and I just did a brushing. I will continue checking my levels tonight and tomorrow morning, then will follow the 24 hour guideline and cleaning as outlined in Pool School. I recently removed and thoroughly cleaned the lights and niches, both of which appeared to be harboring the yuck.