Personally, I found this thread (which I read completely) totally confusing and unhelpful. One side insists that phosphate levels are crucial, and one says to ignore them. I don't know who to believe.this is/was a very insightful thread regarding phosphates. i think the idea of phosphate control as insurance is one to think about - especially if you can't keep track of your pool as consistently as you might like/have time for. i really see why it would be important to someone who cares for many pools on a once a week basis to try to stay ahead of the algae any way he can. thanks for all this great stuff!