What you guys think? 70gal cube or 45gal cube?

[Myka]

If you use a LumenArc (my choice pick) or a LumenMax it will spread the light 30x30". They are "specialized" reflectors designed to spread the light evenly over a larger area. They are best used with a SE bulb, but will do ok with a DE. J&L carries the LumenArc as well, but they aren't on the site. Email them for a price.

You already have the HQI ballast, just buy one of these reflectors, and a SE socket to go into it instead of a DE socket, and pick a compatible SE bulb to run on the HQI ballast for optimal performance. Or just use your current DE socket. It's just that the reflectors will be designed for either the DE or the SE so you have to decide before you get one.

Also, the Lumenarc has two 4" ducts built into it for optional fans. You can also buy glass to use with it for DE assembly. The LumenMax will not accept glass.