I developed Mustard Algae in my pool. I was surpised because the Chlorine levels had remained consistently within the correct range.
I brought a sample to a pool store, they gave me some phos free to dump in the skimmer which I did and I also brushed all of the algae away. A few days later Algae is back and pool store says I am still over 5000, but they can't really tell how much over.
They are telling me it could be casue bu the fact that when the pool was new I used Jack's Metal Control per the installer to prevent stains and it turns to pure phosphate when you stop using it. We do get some leaaaves and what not in the pool but it doesn't seem to be enough for this.
Any ideas what the cause might be before I buy a large $45.00 bottle of Phos Free??