there are many algae eaters out there depending on the type of algae.
I believe crabs are a bad choice since they do minimal damage if you come up with an algae break out.
I'll say turbo snails work great, but do not buy a whole bunch or they will die of starvation.
Some crabs are ok, it adds life to the rocks. Don''t depend on them to do all the work
You also have Conchs that will eat Cyano on your sand, even mix the sand.
You have emerald crabs that eat bubble algae.
you also have some types of fish that feed mostly on algae.
For new tanks, somce crabs, some snails and some conchs will do the trick. then make sure your water quality is as good as you can get it to be.