fighting mustard algae

[chem geek]

The chlorine will drop during the day. What's more important is how much it is dropping at night. Just add more chlorine to raise the FC again. Shocking is a process, not a one-time dose. You'll maintain the shock level until all the visible yellow/mustard algae is gone and your overnight chlorine loss is normal (usually < 1 ppm FC but at the higher shock level it might be OK to be a little higher than that) and then to be sure you'll keep it at shock level for another day or two.

As for those other methods of maintenance with higher FC or polyquat, etc., those may not be necessary. Let's see if we can completely get rid of this so you won't have to use other maintenance methods. Those methods just keep any yellow/mustard algae in check and they don't completely get rid of it.

[Kateyru]

Ok, I think I've got the plan. Shock at higher levels till no visible algae and overnight chlorine loss is normal...just like regular shock process.
I wasn't sure it was possible to get rid of all the mustard algae since I can't get pool light out.
I think this will take awhile and lots of bleach. I added 4 jugs of bleach (182 oz. jugs) last night to get FC = 40. This morning at 8:30, FC = 33.
Off to Dollar General (best price on bleach there and at Costco, btw) to get lots of bleach...should have bought stock
Important question, would you swim in this, FC = 40? It is hot as hades in Alabama!!
Thanks so much!!!!!!!

[Kateyru]

At 12:30 pm, FC = 37 so I added 2 more jugs (182oz. each) of bleach then measured pH. I added 50 oz. of acid last night based on pH of 8 BEFORE I started mustard algae shock. The pH is currently over 8. Do I add more acid?
Thanks.

[PoolDoc]

You need to keep your chlorine high -- I haven't re-read the thread, so I don't know how high -- but you ALSO need to keep your pH in range. Add some acid, until it's below 7.8!

[Kateyru]

Okay. What about TA which was 48 on 7/31?
Thanks.

[PoolDoc]

TA is related to pH, but not the same: you can have hi TA and low pH, hi TA and hi pH, lo TA and lo pH, and lo TA and hi pH!

You need to lower your pH! Once you do, you need to re-test your TA. If your TA is excessively low, you'll need to add bicarbonate, and THEN probably lower pH some again.

[Kateyru]

I added muriatic acid when I was at home for lunch. Will re-check pH this afternoon and get it down < 7.8 then test TA. I'm continuing to shock at mustard algae level. Pool water seems to have gotten way out of whack...
thanks much!