Whaaat??? You guys actually have algae???? :shock:
OK just kidding.
I know that there are those artificial scrubbing pads they sell for cleaning glass. One is green for glass, and the other is white for acrylic. The green ones always looked to me to be the same as the ones to scrub pots, and I've always been afraid to try them. So I buy the white pads at the LFS and use them for glass. I have never scratched the tank with the white pads. If the algae isn't too stubborn a paper towel can be used. For really stubborn cases, I use a straigh edge razor blade. With the pads, don't pick up gravel with them when you get close to the substrate. Turning the pad around to the backside will remove the gravel from the pad.
For whatever my otos don't pick up, my usual weapon of choice is a razor blade, but I find the replacement pads for Magnavore magnets really nice for algae that's easy to remove. They do a wonderful job with or without the magnet.