Ventilation

I have a 4x7x7 Mylar tent that i intend to grow in. I am planning on using a 600 watt HPS light. For ventilation i have attached a duct to my hood with the light which is attached to a 136 watt squirrel fan that has 440 CFM which is then connected to another duct that runs into the attic. It is setup the suck in air from the hood and blow it out into the attic. I also have some clip fans and oscilating fan i plan to add inside the tent to create mroe air circulation. My question is will this fan be enough to keep the tent cool? Or do i need to pump in fresh air from outside? I have attached photos.

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I would say you'll probobly want to pull in fresh air from outside the tent.. Turn the light on and the vent system for a while and see what your temps hold steady at.. My box is homemade and the whole surrounding bottom 1" of the box is open to outside the box. With only the exhaust fan of my bathroom sucking from the top of the box, my temps are great that way...Goodluck.

Thanks. We will give it a dry run once we get the ballast in. We were originally thinking of doing a 1000 watt but realized it might be a little over kill and to hard to cool but the 600 would work well. So we had to send back out 1000 watt ballast and are waiting for them to send us the 600 watt ballast. But its alright i got a separate room for vegging so i can carry on. Plus i am still waiting on my feminized seeds to come in. I have an identical fan i can use but how often should i run it to pump in new air?

any input?

if the tent is sealed up then yes you are going to want to get fresh air to your plants in order to get a good co2 exchange. your light will be plenty cool, but your plants need to breathe.. if you have a little extra change i would suggest some co2 injection..

these tents are perfect for them because you have a small area to supplement, and if you get a few fans in there you can really crank up the co2 and your production..

Thanks for the input. Are you talking CO2 tanks? and how often should i pump in new air?

yes co2 tanks.. and you should change the air in the entire tent every 5 minutes.

one thing you can do is take one side of the vent tubing off of the hood and use it as an exhaust (so it is sucking air from inside the tent) and then put an intake fan at the bottom of your tent pulling fresh air from the room into the tent

Thanks for the input the hood has another opening on the other side so it is constantly sucking air out as it cools the bulb so all i need to do is add the second part that sucks air in from the outside of the tent. I am also prolly going to hook up a t CO2 tanks to pump that in 3 times a day at 15 minute intervals. but i have a minute to worry about that because I am still in the veg stage right now.