How many of you are keeping invertebrates in your aquarium?

I tried doing the cherry shrimp, but they just did not do well for me at all. Eventually they all disappeared. Started with 10 in a 10 gallon tank with sand substrate and bunch of live plants. Did everything I was supposed to-strictly an invert tank, added filter media from another tank after a few days, didn't use fertilizer for the plants, regular water changes, covered the filter intake tube with a sponge....no idea what happened, lasted about a month. I'm thinking maybe something with the water it is rather hard, ph runs about 7.6 and I don't like messing with the ph, but I thought Prime would've neutralized any heavy metals. One female did have a bunch of babies she was carrying around. I did get a bunch of Malaysian trumpet snails with them as well, and they've flourished, those guys are neat :) So that's all I've got now in the tank, a tank full of MTS lol and 2 rescued neons-that as soon as I can find them for under 2.00 I'll make a proper school of. Tossing around the idea of trying again with the cherry shrimp, but waiting till it cools off a tad since I'll most likely buy them online again. Any tips or ideas what you think I did wrong, let me know. I've also been tossing around the idea of trying out an electric blue lobster. But haven't seen them around any stores(our stores really suck here), and the shipping is insane for them to buy online.