Which shrimp substrate did you use ? Ordinarily, Cherry and most other Neocaridina shrimp don't need any special substrate. It is used for Crystal and Bee shrimp more often. Some of them can leach ammonia for some time, depends which brand it is.
Shrimp also much prefer a well established tank that is at least several months old. They need biofilm, and it takes that long to grow enough for them. Which is not to say they won't be ok, but shrimp in a new tank are definitely not recommended.
You say you are squishing snails ? I hope not in the tank ? Shrimp do eat dead things, but too many dead snails might cause water quality problems. Shrimp need very, very little by way of food.
I feed mine two or three times a week, and they can go weeks without feeding, and have gone weeks when I have had to be away. I'd rather that than risk fouling the water if a pet sitter overfeeds. I have about forty adults in a 5G and they get only a tiny piece of algae tab or a few 1mm sinking pellets when I do feed them. They have a mineral stone they like to graze on, and they have lots of moss and plants to pick at too. Lots of babies now too.
I also have dwarf fan shrimp in the same tank, about twenty or so, and feed them liquid algae and rehydrated dried algae, and microworms. They all get along quite well.
I used Fluval shrimp substrate, because it was good for the babies (rounded, soft pellets that don't get mushy, and it's easy for them to hide in). The package said that it wouldn't change the pH or leach anything. I ran the tank with an old filter, filter squeezings, and borrowed decorations from my established 20 g, and the 10 g was cycled in about 3 weeks. Once it was cycled, I put in new filter media (keeping the old for BB transfer), and waited another week.
I then started catching shrimp from my 20 g. I "worry" them with my fingers in front of their faces, and they pop backwards into the net - it's the easiest way I've found to catch them yet.
I have been giving them one algae pellet, broken up, once a week. They seem to feast on it at first, then munch casually thereafter. It's pretty much gone by the next day. They are constantly grazing, and the males are swimming vigorously.
The snails I squish are about the size of a flea (or smaller!). So I do squish them in the tank, because I can't get them out with my fingers or net. I do a 25% water change once a week, so I don't think the water gets too much of an ammonia spike.
I can't even count how many shrimp I have any more. I have numerous tiny shrimplets, about the size of a half of a grain of rice. Some of the females are so dark as to be almost purple.
Interestingly, about two of the females have bluish eggs on their underbellies, and the rest of them have the deepest red eggs. A few of the shrimp (mostly the males) are red but it looks like they have a blue "stripe" across the back where their midsection starts). I thought it was a seam of the shell (they were getting ready to molt) but now I'm not so sure. As far as I know, I bought all red cherries from my lfs. All of them have looked like text book red cherries (males clearish with red spotting/shading, and the females deep red).
I have java moss and fern, and planted some dwarf hairgrass. The babies have been all over that hairgrass!