Two and a quarter square metres is no longer tent scale but room scale, and the range shows it: everything here is LED, in the 600 to 800 watt class. Discharge lamps play no part at this size, because the power you would need brings in so much heat that cooling becomes a bigger problem than lighting.
Evenness beats peak
Over this area the question is not whether your lamp makes enough light but whether it arrives everywhere. A single panel inevitably leaves the corners behind: the light comes from one point and falls away sharply toward the edges. A multi-bar fixture lays the same power down more evenly, which is exactly why the heavier models in this class are almost all bar fixtures.
What is here, and what the manufacturer states
The Lumatek Zeus 600W Pro 3.1 states 150x150 on its product page, exactly this size. From Mars Hydro there are the FC-8000 EVO and the FC-E8000, the latter also stating 150x150. The AC Infinity IONFRAME EVO8 is the heaviest of the four at 730 watts.
One heavy fixture or two lighter ones
At this size that is a real trade-off. One fixture is cheaper, hangs faster and needs one connection. Two lighter ones lay the light down more evenly, can be dimmed separately when you are only using half the space, and if one fails you are not in the dark. For a room you fill in stages, two is often the more practical choice.
Count the rest of your setup in
Over this area your extraction, your pot size and your circulation all step up, and the lamp is not the most expensive part of that step. Plan on more than one circulation fan too: across a metre and a half, one does not reach the whole canopy.
Frequently asked questions
Why is there no HPS at this size?
Because you would need several, and the heat that produces is hard to remove over this area. LED gives comparable light here at considerably less heat.
Is 600 watts enough for 150x150?
By the manufacturer's own rating, yes, for the models that state this size. If you want more margin or you grow with CO2, the heaviest version gives you headroom.
One lamp or two?
One is cheaper and quicker to hang; two give a more even spread and can be controlled separately. For a room you fill in stages, two is more practical.
