TraceyB,
The algae will come, just give them time

Our steps also have the cut out slits on the sides and they, too, sit a few inches away from the pool wall. I had never actually thought about algae growing under the steps until the day came when I noticed a narrow green band peeking out from around the bottom step. I scrubbed it, got rid of it, and some days later it was back. So I moved the steps.

YIKES!!! A slimy green area in precicesly the complete footprint of the steps. What a mess!!!

There's enough circulation behind the steps, due to their distance from the pool wall, to keep (visible) algae from growing but the slits alone are not enough to adequately move water under and through them. Now that we've cut the holes in the sides and bottom front this issue has been resolved. When I brush the pool I pay particular attention to swishing some water in direction of the holes. I also put the hose nozzle behind and under the steps when I add water.

I suspect there will be some algae growth directly under the bottom step where it sits flush on the pool bottom because it's weighed down and no water to speak of can circulate there, but that's a vast improvement over the several square feet of green gunk we had previously.