Central air conditioning can't keep up

I have a 4'x2'x5 tent inside an empty room in my house. I currently am running a 400w hps, with a cool tube and a 435cfm exhaust venting to the attic. Now I realize I'm creating a negative pressure situation with the central air and the system can't seem to keep up. It's been very hot here lately and the upstairs of he house now goes up to 82 during the day and by electric bills are insane.

What are my options? This will be my last summer grow, so I really just need to figure this out for the next 5 weeks or so. I want to keep it stealth so a window ac isn't an option.

Any form of intake into the tent itself? Passive or using fans?

You could try to runs something like, FAN >>>>> LIGHT >>>>> FAN if you can grab another fan or something?

It's passive into the tent, vented to the attic. I am also running a 250 cfm duct booster fan for the cool tube, this is being sucked from the room and also vented into the attic.

Just vent back into the room instead of the attic. The central air should have no problem cooling the room with just a 400watter. Try it and monitor the temps..

Well the intake to your cooltube you could run another fan to push air to the fan thats pulling air. You know?

Yeah, you need to vent into the same room, or preferably another room as long as a door is left open. Like you said, sending all that air out is causing negative pressure, which draws hot outside air into the room through any leaks in the structure. I run a 400w in my bedroom in a cabinet that is vented into the same room, and it doesn't heat up my room with the door open and central AC running.

Venting into the room is cool if your ac can handle the extra workload but don't forget smell...

easy fix. run a light cooling system this way......from outside-fan-light-back outside.
----> --->------>------>------>>------->

what if your outside temps are high 80,s and humid ?
will it still cool the lights/hood ?
i run two 600,s and still cant figure out the best way to vent/cool them

I find that passive intake, with in-line lights, will work best. But that's just IMO.

I have a similar setup. 400w in a tent within a bedroom. Currently, I am venting out of the tent and into the bedroom (that is cooled by the central air).

My only concern is that I would like to increase the stealth factor and close the door. The thermostat is in the hallway outside the door. If I were to vent out to the hallway and close the door, wouldn't the fans just suck the air through the crack under the door and through the a/c ducts?