drdawg said:I wasn't referring to the ballast heat, but to the tube heat. I would think the extra wattage would increase the heat and probably/possibly shorten the life of the tubes. That's nothing more than a guess since I have never increased ballast wattage to any of my fluorescent fixtures.

Well, I think that is a good guess. I am sure that running the tubes hotter does indeed shorten their life. It stands to reason. The Philips T8 48-inch tubes that I buy are rated at 30,000 hours or higher (some are rated at 36,000 hours). My timers are set at 16 hours per day. My indoor gardening includes November, December, January, February, and March. 5 months. And sometimes half of October and half of April. So say 6 months per year. 180 days x 16 hours/day = 2880 hours. Round that up to 3000 hours per year to take into account some incidental use.

So nominally I should get 10 years from a bulb with no overdriving. I am actually getting pretty close to that in actual use, with overdriving. I am sure the overdriving is reducing bulb life some, but apparently not a whole lot. Certainly not enough to cause me to quit overdriving my fluorescent tubes.

ZM

Well I am definitely gonna try CFLs I picked up a 8 - pack of 100 watt (equivalent or replacement value) CFLs today for 17 $. A real bargain. I am gonna make my own fixture and will have 800 watts equiv. Used in conjunction with reflective film, should do a great job. I shall see.

Was looking locally at 350 Watt (equiv or WE) bulbs yesterday for 19 $ each. That is the largest I could find locally. 700 WE would have cost me $ 38, so $17 for 800 WE looks appealing.

I have also looked at LED. My conclusion is they are useless unless one wants to spend a ton of money.

I have used LED's for three years and have not been the least impressed. The larger wattage ones (not really much wattage but were water-proof) did not last more than a year (Chinese of course) and the really low wattage ones just don't produce enough lumens to be effective. The expensive ones (high wattage) have to use fans because of the heat generated and because I have to use mine in water-prone areas, those are out of the question, regardless of cost. I have not found any higher wattage ones that are water-proof.