Hello, have been on tfp for a while but never had a need to post. I have been fighting mustard algae for over a month now and try to eliminate it by slaming the pool. I thought that I killed all of the algae. I was keeping my fc anywhere from 5-7 for two weeks once I thought it was gone. However we just got an inch of rain and the pool is back with zero chlorine left. I try to keep as many chemicals out of my pool as possible so I haven't resorted to an algaecide like most people use. I test my FC twice a day using dfd powder for accurate readings. I have a Taylor test kit. I have been just using liquid chlorine and my salt water cell for fighting this. I have a fiberglass pool so brushing the algae off is a breeze. Should I resort to an algaecide like yellow out? Thanks.