PoolDoc - Please excuse me for "barging in" on this thread, but I need help with mustard algae also. My initial contact was regarding your wonderful recipe for Intex above-ground pools. Although I found your guidelines well after I set up my little pool, I was able to catch up with the process and have been using dichlor and chlorine as you recommend. TROUBLE IS ... (!) ... For the last week or so I have been battling with mustard algae. I have sanitized, vacuumed, wiped walls & floor of pool, changed and bleached filters, etc. on a daily, if not 8 hour basis - all to no avail. In desperation, I finally "overdosed" my pool with dichlor and chlorine (60 ppm - what the heck?!?). Needless to say, the water cleared up and yesterday I did not see one dot of algae. This morning though, I saw a few "klans" here and there. At this point, I don't know what to do! Please let me know what you suggest. I'm tired of fighting, and if I just need to let the chlorine burn off and then drain the pool, so be it. I thank you in advance for your time and input!