I don't want to add fish as the tank is super super small, i only want to put a soft and a LPS coral.Carbon will definitely help to Clear water but I don't believe it will help with algae management. Carbon is a chemical filter, it will soak up whatever contaminant or medicines is in there.
Algae is normal in the begin.. I had myself some issues too. A good clean up crew once they appear is the best thing in my opinion. You should see first some diatoms.
I'm curious about this Bobbitt worm. If you have fish in future, this may be trouble.
Here you can see the main form of intelligence in my aquarium (and in my flat as well)


