Just make certain that you get the correct Mr. Clean Magic Eraser. I believe that you can get them scented and with cleansers in them. I've used the plain pads and they work great on regular algae but rough coralline algae can shred them. Best bet for coralline algae is the Kent Marine scraper for acrylic or an old credit card.
Once you get it off I'd recommend an Algae Free magnet. Go to their website and check out their
scratch removal kits for acrylic tanks. The kit has sandpaper pads that attach to the inside magnet so that you can remove mild scratches without draining the tank. The pads run from 1500 grit up to 6000. Once you get the coralline off, follow the instructions in the kit and work your way from 1500 all the way up to 6000 grit pads. Your acrylic tank will shine like new. After that, just keep up with the regular algae and if you see any minor scratches you can stick a pad in and buff it out in no time. Works great. Also, be sure to pick up an acrylic cleaner for the outside of the tank. I use
Brillianze that I picked up at Tap Plastics in Bellevue. It cleans and won't fog acrylic. Also, it leave an antistatic finish so that dust isn't attracted to the tank so that it can get ground into and scratch the surface. I wipe the inside with the magnet every few days, the outside with Brillianze about once a week, and the tank looks great.