The 2 X 4ft/8 tube lights are just right for a four by four ft grow bed (I believe you've seen our pictures). For a four by eight foot bed you would need four 2' X 4'/8 tube lights. Anything less will affect the growth of the leafy greens you plan on raising. You want to fully cover the grow bed with light.Originally Posted by Cooper'sConcessions
Don't skimp on lighting. Been there, done that and the result was not nearly as good as having ample lighting. To save electricity you can reduce the number of hours the light is on (minimum 8 hours), but reducing the lighting beyond a point causes less than desirable results. If you want healthy looking greens, rather than leggy greens with reduce leaf size, then use enough light for them to properly grow.
Somewhere on the forum I gave exact numbers, but I don't remember where. It was in response to a small indoor aquaponics system that needed more light and more media. You can look it up under my name if desired.
Oliver