Tubular! Literally that is: the biUbe holds 9 gallons of dazzle in an upright tube. Glass distorts when you bend it but acrylic doesn`t and it`s clearer brighter and stronger too. Five stages of filtration including mechanical biological and chemical will keep your fish healthy with lower maintenanceThe optional LED lighting will make them sparkle even more.Replacable Bi-Ube filter cartridges should be replaced every 4 to 8 weeks. Find them on biorbparts.com and in stores