Does having a vacuum in your grow space cause stunted growth?

So I have some clones I transplanted 2 weeks ago. They had some great roots going when I put them in the grow bags with coco. I have made sure the pH stays at a solid 6.3, the humidity is about 40%, temps in the mid to high 70's, not over or under watering, 1/2 strength nutes... these things just aren't growing at all. Like, i have 2 or 3 new nodes on each plant after 2 weeks, and the new leaves are tiny. but they look really healthy, no curling, browning, discoloration, etc...

The only factor that I haven't considered until just now is this: I have my fan pulling air through the grow tent via my lighting hood. One side of the hood is open and then I have an intake duct coming from my window into the tent, so the cool outside air gets pulled in, circulates via some fans I have clipped onto the sides of the tent, and gets sucked through the light and out the exhaust to another window across the room. The reason I do this is to get new air to flow through the tent, and also it stays a good 5 degrees cooler than having intake/exhaust just going through the light hood. When I zip up the tent, the vacuum created sucks air through the intake but also causes the sides of the tent to suck in, so I know I have quite a bit of negative pressure. Do you think this could cause the plants to have stunted growth? I could put AC through the tent but I'd have to go out and get one and I don't have an extra few hundred bucks to throw down so this is the best way I can do it without raising temps.

Any thoughts?

when you seal up the tent, it will restrict airflow if there is no intake vent, and create a low pressure zone

the tent should have an intake vent on it someplace, usually down by the floor.

the low pressure itself wont harm the plants, but restricted airflow will cause humidity and temps to rise.

you will burn out your fans by making them work too hard, while defeating the purpose, which is to keep the area cooler.

I very much doubt if the negative pressure you are crating would create a lack of basic air in your grow room, you need a certain amount of neg pressure to ensure the smell is extracted. You have fresh air going in anyway so personally I wouldn't worry about it. And yes agree with Dr Klynes, it will make your fans work harder

Dr. is probably right but check your temps in your root zone. Could be under 65 F and that can cause slow growth. At only high 70s around the plants my guess is that your roots are cold. Bring in the cold air away from the roots/pots/res. Hope it helps.

Dr Kynes said:

when you seal up the tent, it will restrict airflow if there is no intake vent, and create a low pressure zone

the tent should have an intake vent on it someplace, usually down by the floor.

the low pressure itself wont harm the plants, but restricted airflow will cause humidity and temps to rise.

you will burn out your fans by making them work too hard, while defeating the purpose, which is to keep the area cooler.

Click to expand...

The tent does have an intake, a duct coming from my window which brings in cool air. The negative pressure is caused by the hood being open on one side and the air being drawn out, but it also sucks in air from the outside. I'm just making sure the negative pressure in my tent won't cause any growth problems. If i hook my intake up to the hood and run it that way, I have to keep my tent wide open to keep temp and humidity down, so that's not an option unless I get a separate AC unit which will be expenisve to both buy and run.

And in regards to the roots, I'm not sure exactly what temp they are at, but the cold air comes in above the plants so I doubt its lower than 65. The tent only gets down to 68 or so during the off cycles and gets up to almost 80 at the hottest point while the lights are on.

Honestly, I'm pretty stumped on what to do. I guess I'll just leave them alone for a while and see what happens. I've never had this problem before, I've always been able to figure out what I'm doing wrong but this time everything seems to be by the book