macroalgae can be very beneficial, but also problematic if not kept under control. It will help reduce some of your unwantedwater contaminants (nitrate, phosphate, CO2) , and can also help with oxygenation. Let it grow, and cut it back when you feel that it is getting to large, and if you have enough, some people will even buy it off of you.
If you dont want it in your display, you could always start a refugium.
:)