I had to get rid of my substrate because it was upping my silicates, it was
like your typical gravel but softer. I now have glass gravel, it's chopped
up and smoothed out of recycled glass. Looks great, and no effect on the
water. That other substrate I used gave me red/brown algae outbreaks.

As for green algae on your plants, get a Pleco! he'll have it algae free
quick! Forget the Corys, a Pleco will eat stuf on the bottom as well as the
glass and plants.