Sue's Pool - ? about mustard algae

[Watermom]

CYA is cyanuric acid which is also called stabilizer. It would probably be a good idea for you to post a complete set of current water testing results taken with a drops based kit. Cary is right - if you go to the pool store to have your water tested, don't let them talk you into buying a bunch of stuff. And she is also right that one dose of shocking won't cure it. Keep at it for another couple of days and run your pump 24/7 for now.

[JohnInSoCal]

I had mustard algae and had a heck of a time getting rid of it. It wasn't a bloom, but it would grown on walls, steps, etc. and be back the next day or two. What finally worked for me was to add 1 qt polyquat 60, then get chlorine up to 20-25 ppm and hold it there for 2 days, run filter 24/7 and brush a couple times a day. After holding chlorine very high for 2 days I then let the chlorine drop down to 4 ppm, put in another quart of polyquat 60 and it's been fine ever since.

I think the main thing that helped was getting the chlorine up to 20+ for 2 days. Before I would just shock it and let it come down and while it did seem to kill the algae temporarily it always returned later. I have a pebble finish which is worse than standard plaster because this stuff gets into all the tiny nooks and crannies.

good luck.

[Sue's_pool]

HI Everyone!

Thanks for the great replies. Today I added a total of 3 gallons of liquid chlorine shock and one calcium based powder shock. I also brushed 2 times. This seems to have the algae in check so far. I will definitely keep up the chlorine levels and will keep BRUSHING, BRUSHING AND BRUSHING!

I went to our local pool store and the drop test only read chlorine levels up to 5! I ended up getting an advanced type of strip test and here are my results...

Hardness-400
Free Chlorine-higher than 10 (very dark purple!)
pH-7.6
Alkalinity-180
cya-30-50 range

One question still...What is polyquat???

Thanks again everyone. Hope you are all enjoying clear, warm, algae free water in your pools...

Have a great night,

Sue