Cooled reflector question

What type of CFM or "free flow air" is needed to properly cool a glass sealed Easy Cool6 Reflecter, Its basically a reflecter with 2 6" ports on both sides ... I have these two 6" inline duct fans will this be sufficient in a closed system? Fan|---Reflecter---|Fan
By the way its a 250W HPS so its not that hot, the reflecter is totally sealed by glass. Thanks! and rep plus for help

i use a 435cfm to cool 2 600 lumecool aire relectors it works pretty good can keep em 8 inch away for a while then like 10inches later on or the leaves might crisp