what does aqadvisor.com say about the stocking with your tank parameters?
In my opinion, a mystery snail is alright, but if it's algae you want rid of, get another nerite. Mine do tend to munch on my plants though, so fair warning. They also will eat kale whereas my nerite will not. Then there's the body outside of the shell. My betta has stopped picking at their eyes for the most part, but it does happen on occasion.
I've also had ghost shrimp. I never had a visible layer of algae to tell if they were doing anything, but they do have a smaller bioload than a mystery snail if you get like 6. My betta did kill one of them and possibly more...I never found some of them. Some died, but now I have none.
So long story short, go for another nerite. They're pretty great! If you do get a mystery, just fair warning that they may eat away at your plants.
My 20 gallon community: 2 Mystery Snails - Arnold Sluggenator & Goldie Brawn, 1 Zebra Nerite Snail - Poop (my pet name for my boyfriend), 1 African Dwarf Frog Juan - Frog, 9 Male Endler's Livebearers - Cloudy, Clyde, Conga, Darius, Frank, Lemon, O'Rien, Peephole, Urkel & Various live plants - anacharis, anubias, hornwort, java fern, java moss, narrow leaf chain sword, water lily, water onion. The Prize Jewel - Dragonscale Crown Tail Betta - Sylvester "Sly" Capone