I am going to experiment with my first MH (HQI, what does that stand for again?) setup. I purchased a double-ended 250W lamp with ballast from "fishneedit" on eBay to start with.

  1. How much heat would this 250W bulb likely generate? What about 70W, or 150W? (Not sure how to qualify this, actually, other than subjectively...)
  2. Are the fixtures, ballasts and/or bulbs heat sensitive? (That is, if there are hot days of 90+F where I am, will this cause issues with the light itself?)
  3. Would the 250 (or 150) be "ok"/"too much"/"just right" to use over a 36x24x24 (LxWxH) or 36x24x16 pressurized co2 tank?
  4. Are there any good rules of thumb to keep in mind when first using an MH setup?


I realize that the height can be raised or lowered to adjust PAR levels. What is a good starting height?