Bob...hehehe
Harley...
Hair algae is an opportunistic algae...when it is starved of the needed nutrients...it dies...and decays creating more nutrients to grow again...
You have to break that cycle in your tank with multiple water changes using RO/DI water, and a cleanup crew (snails) to consume what does grow, which it will most likely always be present in a system...check your lighting quality (bulb age), feeding regime, any other issues which may be contributing to the growth, phosphates and nitrates.
Hair algae can be whooped back into control...it takes a little time, lots of salt mix and close monitoring...