Yellow mustard algae & Yellow Out vs Yellow Treat vs Mustard Master

[angiedubberke]

I take care of a 60,000 gallon swimming pool. There is no evidence of yellow mustard or any algea in my pool the pool is crystal clear and tests perfectly. We have a chemical called "Yellow Out" . I have been told to use the Yellow Out as a precautionary tool to work against getting yellow mustard. I have read about the product and know that it is supposed to be used with chlorine. I also think its going to make my clear water cloudy. This doesn't make any sense to me. Any thought??

[PoolDoc]

Yellow Out is an ammonia salt, probably ammonium chloride. I think they used ammonium sulfate at some point over the product history, but I don't believe that's the case now.

If you follow the instructions on the bottle, AND raise the pH to 7.8+, you'll end up with 2 - 3 ppm of monochloramine in the pool. Monochloramine is the least irritating of the 'simple' chloramines or combined chlorines that the swimming pool industry talks about. It is VERY effective against mustard algae.

BUT . . . being LESS irritating than dichloramine or nitrogen trichloride, is NOT the same is not being irritating. 2 - 3 ppm is somewhat irritating to all swimmers, and extremely irritating (severe itchy skin rash) to some. As a result, you'll have to close the pool while it is in use. Then you'll have to shock repeatedly to remove the monochloramine. Also, if you have an ORP system, you'll have to disable it while the Yellow Out is in use.

Using it as a precautionary measure is not even something that I think the maker would recommend. It's effective in removing mustard algae IF you follow directions PLUS raise the pH. But if you use it, you need to be ready to pay the piper, with respect to the severe side effects.

Bottom line:

1. Monochloramine is VERY effective at killing algae,
   whether you produce it using Yellow Out or aqua ammonia (like old-time service guys did).

BUT:

1. You cannot swim while it is present.
2. It is hard to remove from the pool.
3. It tends to be a TEMPORARY fix, with mustard algae returning quickly.

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General note:

• There are 2 common types of mustard algae treatment: ammonia-based and bromide-based.
• Yellow Out, Mustard Master, Stop Yellow, etc are ammonia based treatments.
• Yellow Treat, etc are bromide based.
• Ammonia treatments generate chloramines (combined chlorine). IF you follow directions carefully, monochloramine is predominantly produced. Otherwise, you may produce dichloramine or even nitrogen trichloride, which are ineffective algaecides and even more irritating than monochloramine.
• Ammonia based treatments work as described above.
• Bromide based treatments convert chlorine pools to bromine pools, at least temporarily.
• This conversion either partially or completely prevents the chlorine stabilizer in the pool from working.
• The result is greatly increased loss of chlorine to sunlight.
• Eventually, continued additions of chlorine convert the bromide to bromate, which is inactive.
• It may take weeks or months to fully convert the pool BACK to normal chlorine operation.