Yes u do lose some lumen s. but not very much, u gain it back by moving your plants closer.

I also think that your 268 is big enough for a 1000 watt hps cool tube, but not big enough for a carbon filter. (obviously)

I have one, and i clean the glass once a week to make sure efficiency is kept up.
SheCutEmDown Reviewed by SheCutEmDown on . Cool Tube? i have a question about cool tubes. well i few questions. When using one do you lose any lumens? and if so is it werth it to have one? i'm not to the point yet where im ready to use hps but it wont be long befor i am. Is this fan 6 inch In-Line Fan 268 CFM EliteHydro.com larg enough for a 250 or 400 watt hps wit cool tube? Slowly but sure i'm figuring everything out. thnx for all the help Rating: 5