I was shocking my pool and the cya was around 70 so it required a lot of chlorine. Also, I wasn't able to maintain the shock level because of work so the process took longer. So this one day the pool store guy said, "you sure are using a buncha chlorine." I told him I have mustard algae to which he immediately replied, "mustard algae feeds on chlorine. you are just giving it food with all of the chlorine you are putting in your pool." I stood there in amazement and I'm sure that was reflected on my face. Once he finished his about algae food I said, "you should go to troublefreepool.com and read pool school." Then I paid for my algae food and left.
Wow... just wow.