I work in Clayton and have a 3 gallon planted Betta tank on my desk. The Betta and the plants have been doing great since inception (January). However, I've had poor luck with snails. They just seem to do worse and worse and eventually die. I got a Nerite snail about a month ago and he stays out of the water most of the time. Also I would get a little diatom surge every time I switched out water.
On a whim I decided to bring some water from home and try that out in the tank. The results have been outstanding. The Nerite is now active and cleaning all sorts of stuff. My usual diatom spots are still clean a week later.
My home water is from a neighborhood well south of Eureka and had GH and HK in the 18 - 19 drops range. I end up cutting it 50/50 with water I get from Schnucks from their Glacial Water stations near the produce isle. Glacial says it's RO/DI water and at $.60 a gallon a 3 gallon jug won't break the bank.
In any case I'm just sharing in case you are having difficulties in your tank with diatoms and snails.
This won't help with the diatoms, but you can add a little crushed coral into your substrate and the snails will do much better. The calcium is good for their shells. I'm on Wildwood city water filtered through a carbon block filter.