My ramshorns and pond snails and MTS all live together (with shrimp). I got about 5 rams, and now there's a whole bunch in my tank. The rams were added after my MTS and pond snails.
About four to five months. I have a lot of plants and I just throw food in the tank in the morning to feed my shrimps and everyone else comes in for a meal too. So nothing too special. My pond snails are the least abundant I think, but they're always at the top usually among the duckweed roots, and I remove lots of duckweed every week or two, so maybe thats why there's not as many.
Seems to me there shouldn't be out competing for food. The snails are not being fed enough plain and simple.
don't MTS eat other snail eggs?
I've noticed it's MTS -> Ramshorns -> Trapdoors in my own tanks. The MTS just gets to food a lot quicker, and usually crowds out other snails from getting any to eat.