To continue on the CUC; Clean Up Crew, the most efficient detritus not algae detritus eater are the Babylonia Snail. Big, very hardy and fun to watch as they're racing toward that piece of food that just fell on the bottom.
They also multiply if you feed enough, i had tons hundreds small babies that roamed the sand, so several generations to replace my original ones, but they're long life ones, 2 years + for snails . You don't need that much because they're pigs and eat a lot. more food means they'll reproduce and that's what you want, instead of buying every 3-6 months for new ones.
They're similar to the nassarius
Who are not quite as big and doesn't have those blotchy spots. Its actually one of their many names Blotch snails=Babylone snails
One of the detritus least useful is the Brittle star or Serpent Seastar
See that nice big hole, when i say least useful it means that it will eat and then digest for days if not a week before eating again, I was always intrigue by the sheer numbers we see them in the ocean and living together, in seem relative harmony. Then researching i found the why so many can coexist so harmoniously together. eating and having days to digest, they're aren't really in competition.
I also means you can have several ones in your tank and they'll be fine, BUT; as efficiency goes to help you clean the tank bottom; better leave it to the snails like i said the most efficient at it, but still interesting to have as diversity. I had 7 in my 150 G tank. But again feeding them helps and they'll reproduce as well.
Another usefull guy is the cuke, sea cucumber.
Mine was big and a problem. I found out that before they split, which its one way they multiply; they need to beef up their bodies to survive while a new mouth or anal track is being formed after the split. They need it because that process can take several weeks.
And in my case the huge cuke was a problem because it took him a year just to beef up and the split in 3, so that meant the mid section had a mouth and the anal track to replace.One of the segment died with no ill affect on my tank by the way; A huge fear by many who don't risk this wonderful cleaning machine.The other 2 survived very well.
It processes sand like the earth worms, it transforms poop and what ever else it eats in the sand into its primary elements and helps redirect resources in your tank. It cleans your sand like no other.
The risk are minimal if you have a big enough tank because the cuke need sand to clean and enough to survive. Forget the 50G tank for a cuke, depending on the size or both cukes and tank you need a heavy bioload to keep this one alive and to split even.