on a side note, the pool filter was off since Thursday around noon apparently. I started the system on "filter" before vacuuming. One return was not functioning. After 10-15 seconds (about the time to realize it and to walk to the return) it started blowing green powder into the pool for 4-5 seconds and then clear water.

otherwise, I am going to use the Phosfree. It says run filter for 48 hours and then to retest.