usmc ive heard you say this multiple times but i never said anything cause i dont like correcting people. Microalgeas are the small single celled algeas that grow on your glass and your lr, macro algea are the ''plant'' like algeas that people grow in there sumps.
people grow MACROalgea in there sump so MICROalgea doesent grow in there main tank. macro algea takes nitrates and phosphates out of the water and it also puts in oxegen.
Roger chances are your live rock already came with some macroalgeas on it. if you see any plants growing off your lr those are macroalgeas. The best algea for the sump is cheatomouphe. If grows like a brillo pad and is very easy to harvest.