Hello. The other day I entered the ugly phase in my first saltwater tank adventure (diatoms I think?) on my sand bed and glass. Now I am noticing little green strands that almost look like grass on the glass. Could anyone let me know what I am looking at, and suggest a clean up crew? I have read astraea snails, turbo snails, and hermit crabs are a good place to start. What is a good ratio to have in a 40 gallon?