Snails will eat some growth - but then you're left with glass with "snail trails" running all over the place.
I've yet to see a tank with enough snails that will keep the glass "clean" enough for most hobbyists. We like that glass CLEAN
A magnetic algae remover is by far the easiest way to keep the glass clean.
If you have a Magfloat cleaner - good for you.
If you're reaching in the tank to scrub glass - take a look at the Magfloats
They are a real time saver and do the trick !