F/S calcium reactor 24"high x 6"dia with bubble counter, mag3 pump for circulation and with ARM media. I bought this unit from Ted (xtremereefer) 8mo ago; and he said it was custom made by georeef -- I think that was before he when big time. The reactor is big and I think it can easily handle above 500g tank. I'm only selling the calcium reactor no C02 and regulator. I'm selling this unit because I just bought hyacinth monster korallin 4001. Price is $180.