BUT, I don't get that, to me the fan is actually bringing in more fresh are if i have it filter/fan/cooltube because it is a straight attachment of filter to fan where the "better" way you say is actually sucking air through lengthy ducting and the cooltube so it would be drawing fresh air at a slower rate or maybe the same rate but causing my fan to work harder.
Again this is not normal temperature circumstances regardless if i did do it that way (filter/fan/cooltube), it technically would cool my bulb better as he says. Also how could i not be bringing in enough fresh air or not have negative pressure created? Its a 30 cfm tent and im using a 190 cfm fan/filter so im pretty sure regardless im bringing in enough fresh air. Did i cover myself on all angles here?
Please explain.
extracting/sucking air (negative pressure) is more efficient than pushing air when it comes to removing air from the space
negative pressure also helps control humidity better
if you push/blow air, (positive pressure) the maximum amount of air pressure the space can hold will need to be reached before air leaks out or is removed from the space
it is less work for a fan to remove air directly from the space (suck the air out) this instantly causes a negative pressure
air will flow in the direction from outside the tent to inside the tent
the result is the air is replaced quicker this way
imagine you have a fish tank of water its 3/4 full , you can add more water and keep adding water to cause the tank to over flow
this will cause water to flood out, eventually all the water will be mixed in with the new water
or you could suck the 3/4 full tank of water straight out and replace it with new water continuously
when using a 2nd fan to directly cool the lights it is ok to use positive pressure and it has advantages
but this is only when you are using 2 fans overall
one to cool the lights
one to provide air changes (co2) and control humidity
if you blow/push with the second fan
1 you do not need a 2nd carbon filter , the air through the lights will not come into contact with the air in the grow space because the positive pressure in the cool tube and ducting
keeps the air from the grow space entering the cool tube so no filter is needed less resistance less cost
2 the air space inside the ducting is small so the positive pressure can build up almost instantly
3 you can take air (cold) from outside and this will cool the lights more than sucking warm air through them from the grow space, some folk with lots of lights use an air conditioner to blow cold air through the lights instead of a fan blowing
4 the hot air does not come directly in contact with the fan
when people only use 1 fan, extracting makes more sense because the 1 fan is doing all jobs
cooling the lights, bringing in new co2, controlling humidity
using 2 fans separates the jobs between the fans
if you only had 1 fan pushing air through the lights
it would cool the lights quite well but it would not bring in new air very well or control humidity very well compared to extracting
peace
but gotta keep the MRS. happy or I can't grow period right lol. Didnt want some huge thing in our bedroom. If it was just me and my bedroom hell id sleep on a single bed and fill my room with plants aha.
See it all the time 
