400 watt HPS over heating issues

Greetings friends, It's been a while but I'm back and trying to set up my first legitimate grow chamber. The dimensions are 2'Dx3.5'Wx5'H flat white painted walls. I have a 400 watt HPS light with a magnetic ballast and the light is housed in a 6" diameter cooltube I have a Eleicent inline fan extracting about ~150 CFM, it was set up to pull air from the chamber then extract it to the outside room however the chamber was reaching temps of about 97F, so i made it closed loop, pulling air from the outside room through the fixture then right back out and this brought the temp to about 95F.
I've tried all kinds of configurations for better airflow and am running out of ideas. considering the size of the chamber i don't want to have most of it filled with ducting and fans.
Is the 400 watt just too much for something this size?
What CFM fan should I be using?

BTW the ambiant temp of the outside room is 78F

more cfm or get a 250 watt light

If I read your post correctly, do you have the ballast in the box ?

If so get it out of there.

Also trying to fit all that in the box, is not going to leave that much room for the plants to grow.

You might need to rethink your setup

You can cram a 600 in there if ya get the airflow down, for example I know someone who has a cab. They have passive intake on the bottom of the cab and air is pulled through the box from the bottom, fan is in the top of the cab pulling the hot air through the light fixture and blowing out the top. temps hardly increase at all with 200 cfm

Thanks for the replies, the ballast was and will remain outside of the chamber. I was also running the fan from outside chamber for all of the test configurations. The light is mounted vertically and exhaust is being pulled from the top.

Generally what CFM is suitable for exhausting a 400 HPS?

To cool a 400 watt HPS just does not depend on the fans CFM rating but the temperature of the air moving through the cooltube.

Remember fans that move a lot of air can be noisy, so if noise is not the issue then I would say go with 235cfm fan.

If noise is an issue I would say get a squirrel cage fan they tend to be quiet, although there are many to choose from.

But more than anything make sure you have some cool air going through that tube.

Best bet is make sure you have an air conditioner in the room

this is why i dont use cooltubes.... there hard to dial in, either the fans too small or its on speed controls because too big, there just hard to dial in sometimes.
get the ballast out of the cab if its in there for sure.

what type of hps lamp are you using? you might want to get the small diameter type, so that there is enough airflow through the cooltube.... or your ducting on the cooltube could be bent to sharply obstructing the airflow. 150 cfm also seems a little small for 400w. some fans inside the cab to keep up airflow would also help prevent hotspots from building up in the interior

Potato_Messiah said:

Thanks for the replies, the ballast was and will remain outside of the chamber. I was also running the fan from outside chamber for all of the test configurations. The light is mounted vertically and exhaust is being pulled from the top.

Generally what CFM is suitable for exhausting a 400 HPS?

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Like I said 200 cfm keeps the cab very cool, can you post some pics? I know what you are going through I went through the same shit. It doesn't completely boil down to CFM either, it is how yo use it, as you know.

I have a grow box I recently constructed! It is 2'x2'x5' and I am using a phantom 400 watt digital ballast and hydro farm daystar hood. Using a ecoblast 4" inline duct fan pushing 160 cfm! Also I have three small fans inside and a light box with a fan in the outside and I am getting temps of 85f above the lights and almost 102f below! I have my fan connected right to the top of my hood! Is this the best way?? Any help is much appreciated! Thanks in advance!