Need to cool flower tent 5 Deg F

Hello community! My flower tent has had some mild heat issues wondering if my fellow RIU'ers have any effective, low dollar ways to cool this room.
tent is 4x4x7
1:150w HPS + 1: 18" Grow, tube fluro underlighting
Photoperiod temp is stabile at 81.3'F
Night temps at 73.3'F
1:6" Can fan and phat philter
1: 250cfm booster fan
1: box/window fan (+/-) 20"

Here's a rough sketch

Is your system sealed? Looks like it from the diagram. Check out my thread, it's my first grow. But I have my temp CONSTANT 73-77 daytime and 64 low at night. And I'm also in Southern CO.

No venting dedicated to my 1000 watt light, so I still have to run the ac in the room.

I've got a 2 way fan in the window, with ducting leading to the exhaust side and another fan pushing air out. Another duct for my intake with an entirely too large fan in the 3rd and 5th pics. If I'm right and you're running a sealed system, you will certainly do better to open it up.

I hope that helps you.

KillaKC: My system is not sealed, it's passive intake. Notice; there's no booster fan bringing air in so I open the doors during the hot photoperiod to get fresh air exchange.

Bullwinkle: my problem is in fact heat and too much of it, not a whole lot; but enough to warrant an investigation into possible cooling practices. I want to take that 81.3 and bring it down to a nice 75-76'F during daytime running.

Running at night won't work cause I want to be able to check easily during the day. I've been contemplating getting some snow/ice and salt/sugar to make a super-cooled water and place that up high to let the cooled air from that float down and cool the top end of the tent slightly. Also thought about doing dry ice, again up high, +CO2 and gently lower temps.??? I realize these would both require daily replenishing = pain in the ass. So Def a ghetto last resort, not the best viable option I'm thinking but what else can do it?

I think you need to vent the hot air out of the room and not just out of the tent.

a small cool tube would help alot... then you could connect your can fan,filter,through the light, and then out the tent.. i also bring in air to my tents through a fan that is ducted to cold air.. ive seen small cool tubes with mini wings on them for about 30-40 bucks... but if you can a 400 would do way better and stay just as cool with a cool tube or some kind of cooled hood... plus no under lighting needed..... ive pulled 14 ounces before off a 3x3 tent - a 400hps in a daystar hood ($90.00) - 9 plants in 1 gal fox farm- flowered when they hit 16" hope that helps..

I've got a cool tube I'm waiting for funds to buy the ballast, then I'll hook up the fans and run all that lamp heat out the exhaust (it will be 1000w!!!) But the 150w is an enclosed system w/ no venting ports, just trying to make this work for now. The booster fan inlet is right near the lamp, considering also getting another booster and attaching right next to the light?

light->booster-> 2' flex ducting-> 2nd booster-> 5' flex ducting w/ 90 deg bend

It's a possibility matchbox, but I'm not sure how feasible it is. I can't have the door open all the time (main veg room needs its un-interrupted dark cycle. Plus the temps in the main room are around 76-73 constantly.) I can't cut any holes in the drywall otherwise I definitely would and (in a perfect world) put a squirrel cage blower at the highest point out. I know there is ample cool/fresh air outside; I just can't grasp pushing/ducting the very cold air (can get to -6 F) through the lightproofed window, around other garden plants, 10 feet +/- and into the tent. Suggestions?

Throttle:
I've got a cool tube I'm waiting for funds to buy the ballast, then I'll hook up the fans and run all that lamp heat out the exhaust (it will be 1000w!!!) But the 150w is an enclosed system w/ no venting ports, just trying to make this work for now. The booster fan inlet is right near the lamp, considering also getting another booster and attaching right next to the light?

light->booster-> 2' flex ducting-> 2nd booster-> 5' flex ducting w/ 90 deg bend

I dont know what you mean by low $ but for around $99.00 you might what to look in to an evap cooler you;; get a 10 deg diff ,but you will raise your hunidity a bit ,but best bang for the buck in your situation look for somthing in the 500- 800 cfm size that should do it for you. some call them evap cooler some call swamp cooler.