I'm pretty sure i've researched this to death and it looks like i'm SOL but I figured i'd ask anyway.

30g live planted tank.
only cherry shrimp are in it.

over 9 months tiny snails have taken over. Must be millions of them in there by now. I've had 6-8ish assassin snails but obviously they can't eat enough or don't like this snail.

Even if the assassin snails did eat the pest ones it would take 100x more assassins to take out this population...

Chemicals usually kill all inverts...which would include the shrimp.

Fish i'm pretty much ruling out since I don't want fish.

lettuce method would take forever and wouldn't be that effective with all the other plants around...

I only feed algae pellets every couple of days for the shrimp which seem to eat them up within a few hours...