Would 2 vipar spectra p600 work well in a 90x90x180cm tent

if you buy a new light -- good heat sink -- lm301 chips -- b or h or evo .. not "c" -- divide watts by diodes -- the closer to 0.25w/diode the better. (EVO = 0.20) -- otherwise whatever they are advertising could be a lie. This is th eonly way you get to 2.7+ umol/j efficacy.. this is the only way you get 50,000 hours of excellent use out of them. This only applies to samsung lm301 diodes. math may be different for other diodes. go check'em out at original manufacturer's website and see the how the diodes were tested.. at what amps, what watts, etc... this is what you want your lights to reflect exactly the same info or they will not last as long and create more heat than they should. This is what equates to a quality light. Prefer a warmer light, but 3400K isn't going to hurt you either, which is what a lot of these lights are... 3400-3500K. The above 3 are way more important than worrying about exact CCT... keep it around 3500K or below, though. Low efficacy = cheap for no reason. it woudl be a few dollars more relative to the prices these manufactruing monkeys buy the diodes at. doubling or tripling their number isn't a big cost. Anything above 0.5watts/diode should be avoided like a dumpster fire. that's a hotplate. ffs.

100w... low efficacy. let's guess 2.1 to 2.3 umol/J i'll work with the lower of the two. 200w * 2.1 = 420 umol/s / .81m^2 = 520 PPFD give or take. This is not strong enough for 12/12 schedule.. it may produce a bud, but yield will suffer greatly. This is only 22-23 DLI. Buds will be larfy and airy, maybe the top cola forms well. A 13/11 schedule will help only slightly... Might push close to 24 DLI. 21-22 DLI is generalyl stated as the minimum. I've never grown anything with so little light i can't tell you exactly what it amounts to. If you want to flower photoperiods, reduce disatance and cover a smaller space than 90cm x 90cm 420/900 = .47 m^2 focus would give you 38.9DLI. This would be lower than calculated more than normal due to refelctive wall distance. push them near 1/2 and work in that space. 3 walls is better than "none." could probably cover ..5m^2 fine. as below this may be 1-5% overshoot, i try to aim high because you can always dial down a fwe percent, but you cannot manifest more light than what the equipment produces. i calculated this stuff at diode, and that is not 100% accurate, but will play out fine in any normal hanging distance context of an LED light. it is actually lower at canopy level for a couple reasons, but that same proportion roughly due to similar hanging distances and geometry of beam angles and such. 18/6 schedule requirements: over 18hours it is 520 * 3/2 = 780PPFD give or take. and, that's a bit too much for 18/6 autoflowers. Definitely don't need more hours. 600 PPFD over 18h results in 38.9DLI 600 / 780 x 100% = 777% give or take.. 2 of these at 77% over 18 hours would be great for autoflower and vege phase in the full area of your tent. Autoflower approved for full tent!

Nah...These are very high quality lights. Grow them without tent.

I was told to aim for 30w per'2. So 120 for 2x2 For yours as said already 300w is right. To answer your question though 2x100 will pose this problem. One wil do a 2x2 so no matter how you hang em part of your 3x3 will not be covered enough. 4 would do ok in a 4x4. Mars hydro tsw2000 is cheap and 315w. Newer models available but I paid 150£ from eBay for a new one from Mars hydro. Overpower and dimmed is always better than full power adequate

Just for example, i bought one viparspectra xs1500 for a 60x60 tent, but then changed my mind and switched to a 80x80 tent. After the first 2 weeks i noticed instantly that this will not be enough for 80x80 in a long run so i bought a second xs1500 and even now with 2 of them it's far from perfect. So i guess even in a 60x60 it wouldn't have been as good as described by them. The light is good so far, but the data they gave you is far from correct, so you need to go closer to the plants and lose coverage. In my experience so far and what i have seen from others, in a 90x90 tent you want a 300 watt LED to get the most out of your space and time which you invest. Everything else in my opinion is a waste of your time, since you could have gotten much more out of it.

250 watt HPS

It'll work, but the coverage won't be optimum. And if you're planning a purchase, I'd advise you to go for a bar design with models such as the Migro Aray 3, Mars Hydro FC-E300 or ViparSpectra KS3000, which, although a little more expensive, will be better suited to your space. However, I don't like to make comparisons with HPS because the approach is different and you can't really make an equivalence per Watt as I see too often. LED equipment, particularly bar styles, are designed to achieve optimum coverage of the canopy while staying fairly close because they heat up less. Power is therefore a parameter that is no longer really taken into account (unless you want to grow with large CO₂ inputs) because the fixtures are calibrated for the spaces they cover. So we'll find fixtures of around 125W for 60×60cm (2×2ft), 300W for 100×100cm (3×3ft), 500W for 120×120cm (4×4ft) and 750W for 150×150cm (5×5ft). The big advantage is of course in the reduction in power consumption.

would work, but this is what you want for a 90x90 tent: https://www.viparspectra.com/products/viparspectra%C2%AE-ks3000-300w-led-grow-light 2 p600 would be the equivalent for a 250W hps wich is what i used in my 2x3 before moving to spiderfarmer sf2000 200W led. for a 90x90 you want a 400W hps or a 300W led