Refugium - Sump - What do I have?

Laugh all you want - It's pretty funny.;D

A friend gave me a bunch of equipment and so I began my Reef Experience. It is a 20gal tank, 18lbs of rock (8 live and 8 base), a 3-4 inch live sand bottom and full spectrum and actinic lights. The TOTAL water in the system is 22 gallons.

1. The first question is what do you call what I have?:-[

My "refugium" is a 15 gallon tank located below the display tank. The water enters via gravity to the left compartment. It then flows into the main section where I have Mud, Rock and Cheatomorpha. Finally, it flows to the far right chamber where the pumps moves it back to the main tank.



Besides knowing what to call it:

2. Should I keep crabs down there?

3. My friend told me to run the light (small 4 watt florescent) on the fuge 24/7; Is that correct or should it be on a timer?

The system is only 3 weeks running now. My goal is a soft Coral display with a few fishes somewhere down the road.

Thanks in advance.

 

Its better looking than most I've seen. What you have there is a refugium and it should be on when the MT light are off. I wouldnt put any crabs in there. Luna

 

Thank you. It is all built by my friends direction.

I got confused because some folks have a sump and a refugium. So I was thinking that since mine is the sump and the refugium maybe there was a different term for it.