DIY

Hello, had made a little grow tent. I'm looking for a DIY ventilation. Tent size 31" wide 2 feet deep

For extraction purposes?

Just letting out any hot air with letting fresh air enter

Could I put a clip on fan on the bottom of tent and one up above to circulate the air? Of course make sure bottom fan is not to close to plants

It has to be light tight during dark period also right?
I think that will be the tricky part without just using a standard can type fan

Yeah has to be light tight.

Something like this: https://www.amazon.com/iPower-Booster-Inline-Exhaust-Grounded/dp/B00CQBFOTS/ref=sr_1_3?ie=UTF8&qid=1527180747&sr=8-3&keywords=inline+booster+fan

Then use ducting in a "S" shape and no light will be visible. Or use light-tight ducting.

Or This: https://www.amazon.com/Cooler-Master-Bearing-Cooling-Computer/dp/B002R9RBO0/ref=sr_1_4?s=electronics&ie=UTF8&qid=1527180804&sr=1-4&keywords=cpu+fan

Or This inside of a duct or mounted to tent and then get some kind of bracket like a dryer vent.