From 1 light I think dialled you could expect to get 5-7oz with the right strain/s from that space and head room, given your actual wattage from the mars300s is around 150, that would equate to 5oz=140grams/150watts=0.93gpw
The yield is limited by the size and headroom of your tent so by adding more light you will likely see a drop in your gpw which will accelerate the more light you add.
1 light 50z=0.93gram per watt
2 light 7oz=196g/300w= 0.65gpw
3 lights 8oz=224g/450w= 0.5gpw
The above calculations demonstrate the diminishing returns from adding more light cause by your limiting factor, in this case the grow space.
Having said that, if you can cool the grow effectively you will get some super dense buds from that kind of wattage!
Oh WOW great ! I also repositioned my tent right underneath the window. The temp outside is about 5 degs . I can open the window and vent straight out with a 50 cm hose. Do you think i can lower temps with a fan also next to the window and get 3 x 300W in there ? I think i can keep temps to 27 degs with 900W LED... !
What your reckon ?
Also for your interest its possible to squeeze 8 x 3 Gallon pots in there !
I'd be inclined to stick with 2 lights then you'd have 1 light over each set of 4 pots and pretty close too
That's also 600w/300w actual over 6sq foot which is bang on 50w p/sqft which is spot on for large bud growth. I've had extremely large buds (leg sized) from 37.5w/sq ft with 600hps's. So at 50w/sq ft you're golden.
I don't think there's any benefit in the extra spend on the additional light as you're already where you want to be with the 2 lights and that means you've got more money for different exciting seed varieties
Any ideas of how to rig my system with the carbon filter ? I was thinking about can bolted straight on the fan sucking air out 50 cm of hose straight out the window.Maybe i can better use cool air drawn in ?
With the space limitations you need to run your vent from the extraction hole to your fan which will blow air through your carbon filter into the room (you can mount the fan directly on top of the filter with duct tape), so you'll be sucking air out via the duct and pushing it through the carbon in this case