Thanks again. So where would you recomend I keep my chlorine levels at?
With 41k gallons the pool is expensive and I wish I had read about the BBB method first.

Why would I get small black spots in my plaster if the chlorine is at 2 like it is and I have the SWG and the mineral cartridge? Scrubbing them out didn't work and neither did superchlorinate. When I added the phosfree I did get them to dissipate but I didn't clean filters so the phosphate levels went way back up off the charts and the black spots came back. They are small, some the size of a pencil point and a couple the width of your pinky with most the width of an eraser. Most are in our ledge where we do have jets.

I love this site.