Invert suggestions?

I need some inverts that will do good in a 55g FOWLR that can clean waste and algae and is somewhat interesting/fun to watch. PS: lots of caves and hiding spots in here .
Here's some I really like
Crown Conch
Fighting Conch
Mexican turbo snail
Blue Leg Hermit
Scarlet Hermit
Peppermint shrimp
Coral Banded Shrimp
Cleaner Shrimp
Serpent Starfish
Sand sifting star
Brittle starfish
Flame Scallop
Sand Dollar
Horseshoe crab
Pencil Urchin
Blue Tuxedo Urchin
Chocolate Chip Sea star
Sea Hare
Turban Snail
Halloween Hermit Crab

I'm also going to add some more sand (can I do that without having to start the cycle again?)

Share your experience with thise inverts

 

I have kept most, if not all and those are my experiences with them.

 

Crown conch might eat your other snails and bivalves.
Coral banded shrimp will likely kill all your other shrimp.
Sand sifting star will eat all your beneficial sand critters then starve to death after a matter of a few months, especially in a new tank.
Horseshoe crabs get huge, but it won't live long enough to do that. They're the same as sand sifting stars, starving to death after decimating your sandbed.
Chocolate chip star will eat snails.
Sea hare requires a LOT of algae and will starve when it's all gone.
Green stars can (and usually end up) eating your fish.
Not sure on the sand dollars, I've only read of one person keeping them successfully.
The Mexican turbos might be the ones that don't live long in tanks, but I'm not positive on that.

If you get a flame scallop, get the smallest one you can find. They don't live long and the larger they are the older they are. They can be difficult to keep and don't really actively clean up anything.

Everything else should be fine depending on what kind of fish you're planning on keeping.

One Fighting conch in a 55 should work fine for sand cleaning. We have 2 in our 55 and have to supplement them with dried algae often. They do also eat leftover meaty food.

 

I had a couple electric blue hermits. Some people say they're aggressive, but I never saw that with mine.