Here is a link with pics and explanations according to "James". Maybe it will help.
Ultra-Violet light. When using a canister filter you plumb them in the output hose and turn it on for an hour or so after water changes. The UV light radiates what is in the water and kills it before it grows.
As for snails, I have had several types in my tanks and have never had a problem with them eating my plants. I have had the common snail "ramshorn" i believe, MTS, Malaysian trumpet snail, which in small numbers are preferred by some hobbyists as they are supposedly good for stirring up the substrate for aeration. I actually bought a mystery snail at petsmart one dumb day. it's actually kinda nice to watch him creep around the tank. Very peaceful and tranquil as apposed to a zippy, busy looking tank like an African Cichlid tank. Don't get me wrong here. I love my africans too.
I had a redtail black shark in my planted tank every since time began but he was too much of an idiot so he resides in my African tank. once i took him out i had an out break of hair algae. which was more of a coincidence but still a factor. I got a new batch of plants that had some hair stowed away in it i didn't catch. I now have 4 oto's in there and things are looking good again. As for the SAE's i have no 1st hand experience with them. They have been reported as getting to big for my size tank and have a rep for being belligerent towards tank mates. So i have avoided them. no clue how much of that is true as they personally don't appeal to me anyway. Check into oto's. they only get about 1.5", are pretty easy going, affordable, readily available (in my area anyway) and school.