why would you wanna put that light far? I have never used those, as while they do the job, i haven't seen yields that match hid. But if u i were to use them I would have them pretty close since they don't give off heat
thanks its my first grow they are three weeks into flowering and are doing fine i had some PH problems after i switch the lights but it seems to be a common first timer problem. my lights are like a inch from them