With 5 plants your talking about 1gpw using the hps. The cfls will only be usable for about 4" of light from the bulb down.
Depending upon your experience 1gpw is achievable. I average around 1gpw from my 400w.
5 autos under a 250w hps is really pushing the boundaries of usable light.
250w gives you about 2.25ftX2.25ft of footprint with about 2ft penetration and 5 autos will not fit in that area. 3 at best.
If you insist on 4-5 autos you'll DEFINATELY need the 400w otherwise you'll get stretchy growth from insufficient lighting.
2-3 autos and choose your 250w with cfls as additional.
J
Excellent point about
useable light. Penetration is always a big issue indoors and a big HPS with a quality (I use digilux 600s) bulb is going to have more lumens, or more useable energy if I'm thinking of it correctly, farther away from the light source....in other words, deeper into your canopy. From reading and from experience with clone cabinets, CFLs are no slackers on heat production, but they are less controllable and I wonder if they are worth the effort.
I've read a lot of posts where the logic is to say 8x23w = ~200watts and is equivalent to 200w from HPS....that's where I would think the 4in of
useable light comes in as opposed to just looking at wattage. Can there be too much light? There is surely an answer and a point at which is becomes detrimental. Until my 10x14 room was ready for 4 600s, my 4x5 room loved 2 600s coming out of 2xxxls positioned 6 inches above the canopy, aside from mild light bleaching from not hoisting the lights soon enough a couple times early in flower...