Need help to cool my light!!!

I have a grow box 70cmx80cmx2meter Length.a 400w MH with cooltube 12cm and for cooling my lamp and my room i bought this fan https://www.intax-hvac.com/vortice-lineo-150-vo-in-line-duct-fan-251p
550m3/h.I've tryed several ways to cool my tube down but no result. 10cm away from lamp the temps goes over 29C.
I've tryed :
1) to suck fresh air outside the window and blow it through the cool tube and take it away from the other site of box .
2)sucking the air from grow box through the cooltube (passive air intake).
i dont know what to do , is the problem with my fan , do i need a beeter one ? any ideas ?please help

i had a similar problem, fixed it by adding a 6" clip on fan right below the bulb blowing with an upward angle. Tho the tube is pulling most the heat off the bulb the glass and such is still getting very hot and transferring the heat, if u blow it off towards the top of your space it should lower the temps below the bulb. Similar to this

http://www.walmart.com/ip/Comfort-Zone-CZ6C-6-in-2-Speed-Clip-On-Fan/21903490

is it ok if i get the top of the plant more away like 20cm where the temp is 25C ?
at the bottom of the box temp is 22C in the middle is 25-26 and 10 cm from the cool tube when i put my hand near it becomes hot

The closer the better, but I usually have a few different stages of growth in flower under my 400w, so some inevitably are farther from the lamp than others. 20cm isn't optimal, but it's better than cooking them at 85+ degrees.

-spek

IF you can get your roots cool your temps are fine, Set up some cardboard painted white and divide the tent into two spaces one whith the reflectors to reflect the light back up and it keeps the area of the pot cool if you are growing one big plant,