look for some jbj's or sealife customs or make it yourself (some types of power compacts), i have a jbj 72 watts for my 15 gallon tank, DONT WASTE YOUR TIME GOING TO ***** OR PETSMART TYPE OF CHAIN... THEY EQUAL CRAP LIGHTS AND CRAP SERVICE AND NO KNOWLEDGE.. support the lfs or this site i would generally get 3 to 4 watts a gallon but im just a beginner