There is no perfect led set up.
Not for what we do, that is...
But the best thing to do, always, is to simply employ as much amperage (V*A=W) as possible. Unfortunately, all the grow lights currently on the market use 3mm leds, which is pretty old stuff... they have that iconic shape. Newer, surface mounted leds, are markedly improved, offering much greater lumens.
In lights such as yours, the manufacturers have simply thrown as many, low power (low lumen) leds as they can fit. The benefit is, those leds are probably worth less than a cent coming out of the manufacturer,... and they can say 90W and whatever...
At some point, someone had taken their ufo apart, and grabbed the name of the OEM, for the leds, it was something bright...
My point is though, the specs for those dees aren't avaliable to the public. Which means... It's not something they want people to know, and its not because they're awesome.
The perfect set up, in my mind, uses just as many watts per foot as an HPS, using dees whose frequency (nm range), is as close as possible to the photosynthetic, um, points of highest effeciency/efficacy at 660nm red and 430nm blu?
AND, those leds are to be placed as close as possible to the plant tops, the points of light as close as possible; to make up for the less than inspiring lumen ratings... Which means a lot of ufo's for a full size grow.
You have 4?
What I'd do now I had them at my disposal...
put all 4 on an area of 2 by 2, the ufp's are look to be about a square foot big, maybe a little gap in between. Then fill that area up as densly as you can sog style (3,4 plants per sq foot), side light the shit out of it, and maybe you'll get some truly nice colas. Maybe you can go with less, I just doubt it. Like apoco said, they don't do 90 watts. Its probably closer to 60W... Thats what a 1K hps puts down per foot on a 4x4 table.
I have yet to see anyone use ufo's like that... If they weren't priced "Out of this World!" you could do that for your whole grow, straight down the side of your 7 feet.
Maybe a ufo per 2 square feet, and fill in the gaps with decent cfl's. Actually in sog that hits your quota of 2 ufos per ten plants, 5 colas in a square foot~ aint too bad, although master sogger memeber gypsy bush averages
3 per foot, which would fit under the ufo nicely.
4 foot wide is really gonna suck though dude. That isn't much room to maneuver in. Knock shit down for as much room as possible. You could air cool it without much difficulty, drawing air in from your ante-room.
Speaking about environment,
I think its not to far out to say, that this is the hardest part of the grow, especially cause you can never know, and even when you do, it can still elude your control.
I do like sealed. It's a little more expensive to start up, but that indoor dual hose stuff is awesome. Most even act as a dehumidifier.
Co2 set ups are expensive, but if you're sealed you can go the natural route, or just wait. The A/C is more important. The A/C will be able to fight the heat put off by your couple hundred watts. What people with HPS's do is to have the lights "outside" the room (just like your intestine is "outside") through the use of ducting, special hoods, high static pressure blowers, and bowel movements.
You really have to go in and test it asap to get it ready, cause eliminating stress is the best thing you can do, which means controlling everything.
Going hydro at some point will also help out greatly.
You have a ton of plants though...
-Have you selected mums yet?
It's gonna be messy till you do, and you're never gonna know which phenos are the best till you see it through.
Idk, this first round, do the density you think will work, find your mums,
and then plant 4 or 5 cuttings per ufo, keep the tops even, and bring that shit in as close as possible, with plenty of side lighting.
Should be alright, but what you got is a pretty small size grow, and I think everyone here also had the ambition of a setup greater than what they had to settle with to start. In a year or two you might be able to really use all those plants you got.
A 600W HPS, vented like I said, would cover the space left over handily though. Just more shit to deal with.
-How did that first grow go? You grew out only one plant correct?
Good luck dude. A lot more work ahead of you, not much coasting.
Let it Ride!
Peace.