Why does everyone want to get rid of coralline? *could not be more confused*
Scrape it off, send it to me.
That said, for the brown algae, not knowing exactly what it is, I've suggested them before, and I'll loosely do it again, hermit crabs.
I have scarlet reef and these: http://www.liveaquaria.com/product/p...1&TopCatId=501
I had an underwater barbershop's worth of hair algae, and they mowed through it in no time, then turning to the brown algae on the sand, and clearing it out like there was no tomorrow.
Do be aware that they will not get the stuff on the glass.
I'm not sure what to suggest here, as my turbo snails ate half of it, leaving little trails of non eaten algae, and my abalones didn't move all that much, eventually making their way around the tank, but very slowly.
The snails also flocked to any food I'd put on a feeding clip, devouring it whole, leaving a whole mess of snail poo. Nonetheless, they're quite active, and kind of nifty to watch.