I had a bout of mustard algae last summer (my first summer as a pool owner) which was preceded by a bout of green algae. This all occurred due to a combination of my lack of knowledge (which hopefully won't happen this summer!) and a power washing of goo from my deck into the pool. After I got the green cleared up and my pool fairly clear which took a good week of lots and lots of shocking and brushing, I kept seeing brown dust all over my steps. It was very fine and would dissapate after brushing, only to return after a few hours. I had never had dirt settle on my steps like that within a few hours, because I ran my Legend pretty much all the time when we weren't in it. My builder told me it was mustard algae and to try the method you mentioned above with the copper algaecide and putting the tools in the pool, etc. I tried it and within 3 days, the "dust" was gone and hasn't returned. I put in a "metal out" product in on about the 7th day to remove the copper. I know folks don't advocate using it, but it worked for me! You may want to consider it if chlorine doesn't solve your problem completely after you try that first, and if you really think it is mustard algae that you have.