Mustard algae experience

[AnnaK]

Since you're able to identify specific spots where this algae tends to recur I wonder if you could try treating it with straight bleach? You could put some into a squeeze bottle (an empty mustard bottle, for instance) and squirt it directly on the spot. You could perhaps brush the area while you're treating it with the bleach.

This would be in addition to disinfecting the water and all equipment, of course. I'm just thinking that spot treatment, if possible, might be effective.

[PoolDoc]

From my experience with mustard algae, I think you'd be better to go with Chem Geek's advice. Spot treating certainly won't hurt, but having Scuba dived in pools with mustard algae, I can assure you that it's not only in places you see, but also in lots of others you don't see, including small cracks and crannies.

If you do hold the chlorine high for a while, be sure to brush thoroughly and then keep the chlorine high for at least a couple of days AFTER all trace of the algae is gone.

BTW, the Yellow Out (ammonium chloride) family of products do work . . . but at a price. You'll have a HUGE chloramine mess to clean up afterwards.

But, the Yellow Treat (sodium bromide) family probably don't work any better than simply raising your chlorine, and they will leave you with an unstabilized bromine pool after.

So, I'd suggest avoiding those -- no matter how miraculous the pool store makes them sound!