If you are looking for algae eating, amano are best. They are slightly larger than neocaridna (cherry, snowball, yellow, blue pearl, etc) but do not reproduce in fw.
If you plan to do snails, I'd at least increase the pH a bit to avoid shell erosion. Use crushed corals or oyster shells by placing them in your filter. You can dose liquid calcium or supplement your snails with calcium enriched foods.
ive been using RO water. our city water is really bad......ph 8.4, hardness more than 280ppm:eek3:!!! and a lot of other weird stuff but i will use 2gal. of that next water change to get all that back up a little bit!!!
any other info on shrimp????? i would like to try them but i know verry little about them!!