If it's a digi ballast with switching capacity then it should be fine. Even if you have a normal magnetic ballast with an ignitor, it will run mh but because it's giving a kick of over 2500v to strike the arc (which it doesn't need) the bulb life would be reduced, although I don't know exactly to what degree or how quickly it would degrade, since I have never seen a test done on the long term effects of mismatching ballasts.

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Originally Posted by ceestyle
Don't be a martyr wasting $100 or more on CFLs to prove they're inferior for flowering pot.