Bubble Anemone

Here's what I used for my 30g

Amazon.com: Finnex External Refugium/Breeder Hang-On Box/Air Pump and Air Tubes, 1-Gallon: Pet Supplies

It's a simple 1gallon HOB and it caused my nitrates, which were always above 50, to drop to constantly around 5 or lower. Just get this and a light for it be under $50 bucks

O wow that's one heck of a deal looks great and doesn't cost an arm and leg like the others out there.

Might have to pick this up when I do my Sea Horse tank.
You don't need sand in your refugium. That is a matter of personal choice. Most refugiums are too small too get any benefit from a sandbed of any kind.