I've had my 20 gallon reef tank going since oct. 2007 with a HOB filter and 2 powerheads but I have really wanted a refugium lately. Would a HOB refugium do the same job or better than the filter? I would put some sand, rock rubble and chaeto in it. Also, I have a mandarin that eats frozen brine shrimp but this would be good for cultivating pods. I just want to know if this method would work better, and does anyone know which HOB refugium is best?