Air exchange rate

I just built a small box to house my germination and or cloning operation.
The box is approx 12 cubic foot inside space and will hold a 2 foot 2 tube T5 light with either a bubbleponic cloner or a plug tray with heat mat.
I would like some input on thoughts, theories or tried and true experience with a small starter enclosure as to the amount of air flow that would put me in the sweet spot(not to low or to high an exchange rate).
I have several small axial 35 cfm fans that in theory would have an approx total volume exchange rate of 3 times a minute unrestricted flow each, if I had to hook up more than 2 of these I would rather opt to purchase a single larger flow unit.
I am concerned with to much or to little exchange affecting the temp and or humidity in an adverse way.
I understand that this is not an exact science and that my individual environment will affect the outcome to an extent, just looking to pick a few brains so I can hopefully do the ventilation on this box one time.

Thanks in advance for your input.

i'm no expert but a steady grower and in my opinion one 35 cfm fan wont quite cut it, i dont think that will exchange nearly as much air as you are anticipating unfortunately. however for the size space you have try to get at least 80 cfms to ventilate and would probably be more efficient as one larger fan rather than multiple smaller ones. thoughthe key is to listen to your plants, they will let you know if its getting too hot, to much circ. and getting dry, or so on. if you're going to toy with a few ideas be sure to watch your rh as some overcirculated sytems can be hard to keep humidity in.

With that T-5 you will need to be at least 30" or so above your clones or you will fry them.

Ask me how I know. LOL

I've been cloning for well over 20 years with T-12's, no prob. Got my new T-5 and promptly baked 20 cuts. I keep the T-12's 18-24" above new cuts. The T-5 was too much at that height.

Wet

yes t-5's are awesome for cloning/propagation. the dont creat to much heat but have a strong gentle light source. wetdog not trying to discredit anything just sharing opinions. in my experience(not all of course) t-5's wont create too much heat and i have been able to clone and start seedlings under a t-5 that is only 8-12 inches away. temp stays cool, and you'll get max lumens without burning. keep us updated on the grow!

Thanks for the input So far.
I was beginning to think my post count was scaring everyone away.
I will have this set up so that the clones will be 14" from tops to tube or closer if needed,I went ahead and set up 4 fans two 40cfm up top for intake running threw a mild baffle system to even out the air flow and two 37cfms on the bottom as exhaust with a slight baffle to draw the air more evenly and help block light leakage.
I figured with the four fans I can play around with the configuration a bit to see what will work right for this box.
As for the light being to close to the tops and burning the little girls I can always ad something in to defuse it a bit if needed , the intake air is a constant 55 to 57 degrees so even in my tents I have to run a heater all the time to keep my temps up, I figure I will be dealing with trying to gain more heat than get rid of it and that can make controlling the humidity a little tricky.
I am trying to have this set up so that I don't have to use a dome to hold the humidity and if my air exchange is to low then the air can get stagnant and could lead to a mold problem worst case,if its to fast then I am sucking all the humidity out and that's not fun to deal with either.
I have read that a lot of people like to have a full air exchange anywhere from 3 to 8 minutes for a grow op but with such a small space and this being used only for propagation I don't know if that's a viable place to start.
Some of you guys or gals out there that have propagation tents and have a fan hooked up to it should have a little bit to share on the subject, I would appreciate the input.

Thanks again