Cabinet vent question

Hi All -

First post on here.

I'm building a cabinet that will have interior dimensions of 24"d x 36"w x 54"h. I intend to put a 250w MH/HPS light and wing reflector in it. Here is my dilemma - I don't have enough space to use a reflector hood or cool tube due to the duct radius requirements at the end of the fixture (ie, not enough space to get the fixture and one duct bend in the width of the cabinet). I am going to put a 150cfm exhaust fan in there with a charcoal filter.

Based on the volume of the cabinet (27cu ft) a 150 cfm fan will turn the space out almost 6x per minute (probably a bit less tho due to duct friction and constrictions at the charcoal filter).

Does anyone out there have enough hands on experience to venture an opinion on if I will experience too much heat gain if I use the open wing reflector on the light fixture? I will have fresh air intake dampers at the base of the cabinet and will exhaust out the top to get proper air flow. If I have to use a sealed hood or cooling tube I will need another 12" of cabinet width to get a 6" duct to turn without crimping it. I really don't want to build the cabinet wider.

I know my dimensions/layout are accurate as I am using AutoCAD to design it.

Thanks in advance.

in my opinion...in a small space like that you are gonna definitely need a cool tube. mh and hps light produce A LOT of heat. 150 cfm fan will not be enough without a cooltube

You can get away without the cooltube but you're looking at temps of 15*-20* above ambient temp. Long story short if your ambient temps hit 75* you're in for some serious hurt in the garden. I am running a 250W HPS in a 2x2x4 with a 170CFM 4" inline fan and it's not easy keeping temps down. I'm running at 75% until I can figure out how to keep the ambient temps stable. My veg and flower boxes are in my laundry room and there are no vents in or out of the space and it happens to be part of the garage. This all makes for some wild temp ranges and is crappy as hell even during winter. Now you can get away with high temps as long as you have plenty of fresh CO2 coming in but pests love high temps and you will be watering much more often as well.

Look up the Diy cooltube with a Bake O Round off ebay or hurricane glass. Either one will work your tight space.

Passive intake in the lowest spot you can manage and twice the size of the exhaust. Put the active exhaust as high as possible to vent as much hot air.

Or just buy some LED's and don't worry about fans anymore

Thanks for the thoughts guys; you have given me a few things to consider. The LED light is intriguing as the cost of the HPS/MH fixture with a cooltube plus a more substantial exhaust system might help offset some of it.

no leds still get hot and still need venting a lot less than hid tho

Yeah I'm building a 2x4x5 cabinet at the moment and I've pretty much given up finding a cool tube to fit. Even a Pyrex bake a round is too long to fit across the cabinet without either crimping the ducting or custom building a pvc ducting rig.
So fuck it, I'm just gnna get 2 chap Ebay 300w led panels and save my sanity