There are things you can do to keep algae out from under and behind your steps. Take a look at the link in my signature (Step Weights), it might give you some ideas suitable for your steps. When you brush pay close attention to where the steps used to sit, that's likely your algae source. Keeping the water at shock level will kill them and with the pump running they'll eventually filter out. But you MUST maintain shock level of 15 ppm until your chlorine loss is 1 ppm or less overnight. And definitely scoop up what floats to the top.

Had I known about those dirty steps at the beginning of our discussion, or that you've had patches of algae coming to the surface for weeks, I would have advised you to shock the pool right away and we might be a little ahead of the game.