Being a newbie--I just found this site after 1/12 years!! I had them set up my tank because I knew nothing about a salt water tank--Have learned a lot over the past 1 1/2 year. A lot from you ugys-thanks--anyway-I see everyone seems to have a refugium, I have a sump underneath my tank, of course, 180 gallons, a skimmer, of course, but no refuguim? I do water changes every three weeks, but I need help with my nitrates. I read thats what it is for. Why did he not set me up with it? My sump is only about 2'x18x18 " deep. We had it built over a 6' cabinet that we already had( turned a bar area into a tank holder.water supply there already.