You can calculate the water volume in gallons by (in inches) (length x width x height)/231 so 48" x 13" x 21"=13104/231=56.7 gallons ... oh and welcome aboard....
don't underestimate how lazy I am – the street address for the house i grew up in was 231 - can't forget that # and the calculator is literally closer than my keyboard and probably less work then going to the RC and looking for the .... I've already typed too muchOr if you're lazy, like me, just go to the ReefCentral Tank Calculator. Yep.....56.7!
Welcome to the site.Just stumbled upon the website, so i registered. I have a 20long tank with 2 oc clowns, and a fire fish, Bunch of different zoas, a few mushrooms, green star polyps and some xenia pom pom.