You need two mystery snails to get a clutch of eggs, and those don't usually hatch-or if they do the babies are quickly eaten IME. Only times I have had clutches hatch was when I removed them from the tank and tried to hatch them, and that was with mixed results. My fav tool for cleaning glass (in and out) ia a MR Clean
original eraser sponge (or the knockoff brands that have nothing added to them). It does a great job with diatoms, algae and hard water stains, sometimes depending on the stain you have to apply more pressure. Also if the algae is stubborn you can use an old credit card, it works very well on scraping it off of glass (thanks
@WhistlingBadger, at least if I am remembering correctly you suggested that back at the other forum a long long time ago...lol)