yea a 90w UFO wont cover more then a plant, and your right, next to no heat, like 1-2C more just under them then in the rest of the room, not like the HPS that made my temps jump from 22-24C to 34-36C and around 32C after I got the 150mm ventilation on, and 30C when I did run it at night, fist with a cool hood on the 600W I got it down under 30C (24-28C depending on outdoor temps)
door is right, you can either try to find some tick rubber matting like I did (I had it at work, on roles, so easy)
but a shop that sell curtains and carpet`s aso often have all kind of stuff in role`s also big hardware stores like them Walmart they got in the US, here in DK we have Silvan, they also have some tick rubber/plastic in black on roles and other colors for that matter
or try to google it, be creative the dust door will provide you with the tick zipper with glue on its back (remember to have a total clean material when you add it, I used 99% alcohol to clean my rubber mat and it have lasted a year now) and if it fall of its cheap to replace agin
400W or 250W depend on a lot, with a 125 ventilation Im sure you could keep a 400W specially in the north
a cool tube would be a very clever move IMO with a 400W not only for heat, but also so you can keep it close to the plant`s as that is so important with all artificial light
so with a 125mm vent and a cool tube/hood Im sure heat is controllable then it more come down to space and plant number a 400W can cover 90x90cm roughly and I would say anything from one big plant to 12 tiny once in a SoG, but most common 2-4 a
250W is only good for one I would say maybe 2 smaller once with some CFLs at the sides
go for one that can run both MH for Veg and HPS for flowering or use a few CFLs for Veg. and add the 250/400W in flowering (depend on your budget and how many plant`s you want and space aso)
air pots is ok, I don't like em that much tho, well I don't dislike em, but I have`t seen any thing specially/notable from em compared to my other square pot`s but will be fine all the way just like the square, what is important is to have pot`s that match the size of your plant`s/Veg time and have good drain hole`s
Slip