I have no phosban reactor on my tank (180) and no hair algae to speak of, Seachem Reefsalt is the salt I use. Lights on for 10 hours a day. no refugium, running 1 cup carbon/ 100 gallon water.
I think algae can be linked to the color spectrum of lights you are using.. I have noticed over the past few months tanks with t5's, 20K- 12K dont have near the algae the tanks that run the more yellow spectrum.. I noticed this especially in my holding tanks (10K).. There is a thick layer of brown hair algae, but not in my main tank which is T5.
Even in the wild you dont see hair algae past a certain depth... maybe it prefers the more red/ yellow spectrum for photosynthesis???
But then you come full circle, what you put in your tank influences what you get out of your tank... are you dosing anything? what type of salt? what is the density of your tank? Lights?
for a 500 gallon tank I could see using a reactor beneficial ( all things staying the same).. if anything it would lengthen the time between water changes, I suppose. What do you guys think?