just open the vent flaps on the bottom of your tent and that ought to be fine, it will pull colder air up from the bottom of the tent to the top where your fan is sucking from, creating a nice "ripple" effect up through the canopy.
you can go up to 85 degrees in the day time with no problems. i try to keep it around 80 now, but 85 didnt seem to strain the plants at all. i do keep it about 65% rh in my veg tent and about 45% in my flowering tent, which may help with that some. i did notice going over 85 started to show a few heat stress symptoms, leaves wilting slightly, leaf edges tacoing.
if you're using Cal-Mag +, theres nitrogen in there, keep that in mind when mixing your nutes up.
those seem to be awfully large pots for seedlings. if you put them in smaller pots to begin with they have time to develope a good rootball, if you put them in pots that are too large the roots cant use up all the water in the bottom of the pot and might get root rot from sitting in it, and it definitely isnt oxygenated
