Calcium Reactor 1218 All cell cast acrylic construction Clear lid to view proper O-ring seal Key hole slot for lid removal Needle valve effluent control Pan World 55 pump, bolted to base plate pH probe port in lid pH probe adapter included Auto fill bubble counter 18 x 18 foot print, 24" overall height Holds 50 pounds of media, we recommend large grain schuran type For reef aquariums over 1000 gallons