nerites are great for algea but the oscar will eat them. If you dont have plants you dont need to run the lights that long, just a few hours you can view them. I run mine on timers for an hour in the morning when i'm getting ready for work, on again for a few ours when I get home.
dont think the snails would last very long, maybe a minute at a push 2 minutes. just have to put the lights in the evening, may get some potted plants.