<a href=showthread.php?s=&postid=12243898#post12243898 target=_blank>Originally posted</a> by DarG
That little reflector is not going to cover a 3 ft tank. Neither is the home depot jobber. Most good halide reflectors, larger units, are used to cover 2 foot by 2 foot. If one was going to install one halide over a 3 ft cube for example, they would generally go with the larger version of the quality reflectors. Like the full size Lumenarc for example. Or if they went with the smaller Lumearc or lumenmax, the could raise the fixture up a bit higher and get coverage over the majority of the tank and place the corals accordingly placing only lower light corals at the outsides of the rockwork. The point is that the general rule of thumb is the larger the reflector the greater the coverage. The higher quality reflectors in this hobby are the Lumenarc minis and Lumenarc standards as well as the Lumenbrites plus the Lumenmax 2 and 3 and the new Lumenmax as well as the full size Lumenmax for large areas. Reef Optix is also a nice reflector for 2 foot coverage. The compact reflectors are about 12" X 12" in size with the Lumenmax 3 being a tiny bit smaller and the Lumenarc mini DE being a little larger. Again, usually used for 2 foot coverage. Theyll cover most of a 3 foot area if raised up a bit. Then they go up in size for wider coverage or better coverage of 3 foot area. The reef optix is a little smaller but does a pretty good job over 2 foot area.
Those little retros would be ok for smaller areas of coverage ... they even adevertise them for smaller tanks. But using one over a 3 foot area is not a good application.
I wouldnt use a halide over a 10 gallon anyway. If I did it would be a 70 watt. If you have plans for halides over a larger tank in the future, why not just save for a system that will light it well rather than something that isnt going to give good coverage.