Algae on rocks and plants can be difficult to remove. You can try rubbing the algae off your hands one by one but algae will soon come back and you have to start all over again. You can let nature take it’s own course by introducing a ‘sucker’ fish called “Ancistrus”. These fish eat algae for food and they can help you clean algae all day long. They grow to about 4 inches long but takes a very long time to do so. If your tank is very small, I would suggest you to get several baby Ancistrus.