What to get as a clean up crew 10g

[Drfu]

For your size of tank i would recommend either 1 or 2"trochus snails as they are the "goats" for cleaning up.

I would also as mahawaka said add some nassarius snails if you have a deep sand bed, if you have no sand then no. They do a great job of stirring up a sand bed and are cool to watch popping out when feeding.

Nerites are great for cleaning glass, 2-3 tops

Last is dwarf cereths if you have live rock, these guys do a great job of the glass right at the edge of the substrate, they also can get into cracks of live rock better than others, because they are so small you could do 5 right now.

My lfs sells all snails for 2.99 each so this should cost you about 40 if you have live rock & substrate.

Im not a big fan of crabs as they can and will munch on your snails. Also snails are picky when it comes to water chemistry so make sure you have no copper in your water. Im already assuming you have no ammonia, nitrites and have done a large water change to bring your nitrates way down!