I have a couple of clumps of green hair algae starting to form in my tank. What clean up critter or what type of specimen can I use to resolve this?

I am also going to check what TDS measurement I get from my RO unit and in the mean time reduce the amnt of time my lights are on. My nitrates were very low last week so I need to figure out what is going on before things get out of hand. I am running a refugium with calupera which should help with the nitrates.