I have a 65 gal. tank with the 24/7 light, and love it on the 24 hr. cycle. However, it seems that the light has difficulty penetrating the depth of the tank for good aquatic growth. I had a 24 inch led left over from an old 29 gal. tank, and use it in conjunction with the 24/7. Since I have a glass top, the 24/7 goes over the back half of the cover, and the 24 inch goes over the front half. I can adjust the "supplemental" light of the 24 inch led with a timer, giving me freedom of adjustment + 24/7 light. With this system, I'm going to Co2 injection for more plant growth.