I would never add more than 2 large turbo snails and 2-4 hermit crabs per 100 gallon.. The smallers snails IMO don't do much for algae control and just seem to die quickly. Turbos have a massive appetite. Too many hermit crabs then they will eventually just kill each other or the snails if not given enough space. Perhaps add a few and see how they do and if you need more clean up crew add them later. I've found few is better then many
Check out @reefcleaners. They are a sponsor here and come highly recommended by many. John is top notch along with his products including clean up crews. He has a great chart by tank size on his site that many people use and have had success with.
I reread sections of this every couple months. Great article.
So we're closing on our house at the end of June. Within the next ~18 months, I'd like to start a bigger tank. I have been keeping a 13-gallon AIO nano for just over a year. I love it, but now I want to move up to something bigger. I want to do LPS with a few hardy SPS and-a long way down the road-clams. Where is the best place/source to read about different types of coral and their requirements? I have the Borneman book Aquarium Corals. Is that good/recent enough?