1000 watt bare bulb donut question

what is the best size fan to put under the light?..there will also be 4 ft high cylinder of fence around the fan and bulb so i can keep plants out of light when they grow toward it.

IDK a big one i guess i got like three fans on my shit

12" floor fan if you can find one. Something like this:

will loews have these?...thanks prawn. headin out to get a fan and fencin to go around it.