I think those of you who say reduce feedings, super glue and other methods mentioned have not experienced a huge out break or may not be keeping SPS. They are in plague numbers and they do not dwindle down. Every single one of my sps have some grown in it.
That being said, I'm pretty sure the snails cant survive in my sump. The first chamber is filled completely with macro and pods and I cannot find a single vermetid throughout the sump. Now back into the tank I have millions, down the overflow more millions, then nothing else after the water discharges into the sump. I can get out mostly everything in the tank just not the overflow. I dont think the snails can travel upstream from the over flow to the tank and I don't think the can make it through the sump. So they might just be contained in this area, but I'd rather be safe than sorry. I am inclined to believe they will remain in the overflow and piping because I've seen gorgeous tanks with no noticeable snails in the display, but during maintenance I see the pipes and they are filled with the snails.
I was also thinking of filling the overflow with super salt concentration, but I'm not sure if this will actually work.