Dual cool Tubes or dual bulbs in single cool tube

I am setting up a small flowering cabinet, 2x2x3.

I am planning on setting up a cool tube with a 400W HPS. I also have a 250MH that I was thinking of putting into a homemade cool tube made out of a Bake-a-round.

I plan to have a single 256 CFM squeril cage fan take air through a carbon filter and pushing it across the cool tube.

My question is would it be better to put both bulbs in the same cool tube, one at each end, or would it be better to have two cool tubes, with air ducting connecting the two, kinda of like an S. See pictures below.

I want to be able to run both bulbs in order to make the most of my crop.

I would make a whole seperate tube, with it's own fan, filter and exhaust. I think that if you run both lights through one tube, you're going to run into heat problems (especially in a space that small).

Bump.... I also seek info n this

try a Y adapter with a squirrel rectangle to circle adapter

I ended up building my 2 cool tubes and that join in an area where the electronics are stored so it will cool them as well. The fan actually pulls air through the veg room into the flowering room then through the cool tubes and then out the top.

With this cabinet I have never had to much of a problem with heat. The biggest issue I have is with height during flowering which I try to deal with by doing SWC instead of DWC The two compartments let me keep a mother and clone operation going.

I wanted to post what I came up with in case anyone can recommend any improvements or as a guide to future builders.

I can provide more photos and details if anyone is interested.