LED Grow Lights: Full Spectrum From 120 W to 480 W

Most people shop these by watts because that's the number on the box. Watts only tell you what the fixture pulls from the wall. What your plants actually eat is photons, and that's where the micromole figures come in. Here's how to read them, and which of the fixtures on this shelf lands where.

Micromoles, Not Marketing: What PPF and Efficacy Mean

PPF is the total usable light a fixture puts out per second, measured in micromoles per second. Efficacy, in µmol/J, is how many of those photons you get per joule of electricity. Across the Phytonaut range the ladder runs like this: the 120 W gives 330.69 µmol/s at 2.74 µmol/J, the 240 W gives 697.10 µmol/s at 2.82 µmol/J, the 320 W gives 927.64 µmol/s at 2.83 µmol/J, and the 480 W tops out at 1415.33 µmol/s at 2.9 µmol/J. All four run Sanan and Osram LED chips behind a balanced full spectrum, so you're not swapping fixtures or adding a bloom bar when you flip to 12/12.

Watch out for one thing: those figures shift a little with manufacturing tolerances and test conditions, and we don't publish PPFD maps or square-metre coverage claims for these lights. PPF and efficacy are the honest comparison points. The 120 W also sits at the bottom of the efficiency ladder at 2.74 µmol/J, so if you care about photons per watt, the 480 W is the stronger buy of the two.

Watts Versus Tent Size: Where Each Fixture Lands

The 120 W is the one we'll put in writing as the small-space option, and it arrives ready to hang with steel cables, hooks, rope ratchets and a 3 m data cable. Step up and you've got choices at the same wattage. At 240 W you can take the Phytonaut 240 W with its 697.10 µmol/s, or the Vanguard Hydroponics Cosmos LED Board 240 W if you want a board-style fixture instead of a framed panel. At 320 W it's the Phytonaut 320 W against the Pure Factory Pure LED Q320, which measures 54 cm across, weighs 5.6 kg and is built on Samsung LMB281+ PRO diodes plus Honglitronics SMD3535, IP 65 rated with a power factor above 0.90. The bigger Pure LED Q420 runs 420 W, spans 62 cm, weighs up to 6.4 kg, uses the same Samsung LMB281+ PRO and Honglitronics SMD3535 mix with the same IP 65 rating and power factor above 0.90, and ships with a 150 cm cable, so check your ratchets are rated for the load before you hoist it. The Phytonaut 480 W is the full-room end of the ladder, with the 240 W and 320 W sitting between it and the 120 W. Grab whatever else the room needs, tents, ratchets and timers included, from the growshop.

Hanging Height, Dimming, and Reading Your Plants

Every Phytonaut spreads light at 120 degrees, which pushes output towards the corners instead of burning a hotspot in the middle. Hang it at 90 cm above seedlings and clones, 60 cm through veg on 18/6, and 40 cm in flower once you've flipped to 12/12. Curling or bleached leaf tips mean the light's too close, stretchy internodes mean it's too far. Dimming is a rotary knob on the driver, from OFF to full power, and the driver also supports 0 to 10 V external dimming systems such as the Zamnesia Grow Environment Controller, which is sold separately. Passive cooling means no fan hum at all, so the loudest thing in the tent stays your extraction fan.

Growers call these weed lights, plant lights, whatever sticks. If this is your first small setup, start with the Phytonaut 120 W and dim it down for the first fortnight. If you're already filling a bigger space and want output headroom for the next run, the 320 W is the one we'd pick, and there's more kit in the Zamnesia growshop to match it.