Heat & Ventilation Control - 600 watts in closet?

Hello - we are looking for heat control solutions for our closet grow. This is the second time growing, but first under HPS so we are a bit unsure.

Seeds aren't sprouting yet, we put them into big pots with a mix of seed raising mix and perlite and hope to germinate them directly under the HPS without having to transplant at any stage.

We have a closet on its side - height is 71cm, length is 145cm, and width is 56cm.

We have 600watt dual spectrum HPS without cover (just the bare bulb and a reflective hood above).

We have a vent hole and an intake hole with ducting - each with a fan blowing into them - plus another large fan inside the box circulating air.

Light is on top and there is about 40cm between the light and the top of the plant pots.

Temps remain around 34 degrees C. as it is now, and we are unsure of the most efficient (plus cheap - we can't afford a cooling case for the light bulb) way to get heat down. Is it actually possible to lower the heat in our sized box with an uncovered 600watt HPS? Would stronger fans at the intake and vent holes do the job?

We know the light is damn close, but we plan to do a lot of LSI to keep them growing wide rather than tall. Getting more space is tricky due to stealth needs, so our main question is: is it possible to grow under these conditions? Has anybody done it successfully?

Also, if the consensus is that it is impossible - do you feel the seeds in the pots are still viable? They have been on a 19/5 light cycle for two days in the above conditions. If we have to we could try sprouting them under CFLs before putting them back under HPS. But we are poor and don't want to spend any more money than we absolutely have to.

Low cost, DIY heat control solutions are very welcome... Thank you very much for any suggestions you can offer.

You're gonna want to be able to extract 2x the volume of air in the room per minute. If you do this, you should be able to get temps down to manageable levels. Consider hanging the bulb vertically without a hood (hoods trap heat) with a fan blowing or pulling air from above (or below) the lamp. You could then have a couple larger plants on each side of the bulb (you seem a bit tight on space) and a smaller plant below to maximize your canopy (but you'd have to pull from above and then extract with a fairly decent sized blower). If you don't get a good fan and filter you are going to have major temperature issues.

I did this in a 4x4x6.5 tent and had no major temperature issues just exhausting outside the room and down the hall a ways into my house (used it for heat). Bare bulb. Pulled down 1.5lbs growing trees around the bulb.

Thank you for the tips - wow, you got 1.5lbs from a 600watt grow? That's impressive. We will get rid of the hood, and see if we can hang the bulb as you say... might not be enough space though. But you think it will be possible to manage the temp just with good ventilation in our sized box? Are the seeds likely to sprout now they've been under the 600 watt at ~34-38 degrees 19/5 for two days? Is it best to scrap these seeds and start again once we have the venting more powerful (I've heard heat can cause deformed plants, but it's weed so I dunno)? Thank you

Higher temps are not necessarily bad during veg. It will cause stretching. But in mid to late flower you need canopy temps 27c or lower IMHO.

That said, you can move quite a bit of air with a 6" inline fan ~400 cfm. HTG has one for $75. also check eBay.