Zero snails / Zero crabs?

I'll bet there is something in there eating algae before you even see it.

You may have Stomatella and/or Collinista snails. You may have Amphipods and Copepods galore. The lighting may not be so bright to create an algae problem. You may not have an overbalance of carnivores. All these things add up, but to ensure that a new tank does not get an unexpected algae bloom, some kind of small herbivores are a must. In the wild at the surf zone, I have counted one snail every 6 inches or so. Have a great day.

My current set up has been running about 5 years now & about the only algae I have is the coralline algae growing on the rocks and the back of the tank.

 

I do have a handful of those very small snails Mike referred to.

 

I have a tuxedo urchin, cleaner shrimp and a brittle star fish I love to watch. At one time we had a couple of crabs living in shells that looked like miniature versions of moose horns (no idea what these crabs were called). I also have had emerald crabs that I enjoyed watching hang off the rocks to catch food passing by (along with an occasional reach for smaller fish), they also seemed to rid my tank of any bubble algae that occasionally appeared after buying new coral pieces.

 

I appreciate the input. Maybe in the future I will invest in some crabs/snails purely for the aesthetic enjoyment.