I don't think that I have rain water flowing into the pool and/or spring water entering by accident. I did however add the spring water a few months back... One time!

I could see how I might have a metal problem but the brown dust makes me think I have mustard algae.

I did have enough drops to test last night and this morning. It was 16.5 last night and 15.5 this morning. Is that a significant drop??

PoolDoc and Watermom-- could you have a metal person look at this thread and let me know if this is a metal problem too?

Thanks so much for all of your help!