400 HPS bulb in 5x5 tent

Can I use the light I have (400 HPS) in my 5x5 tent for just 3 autoflowering plants (just started the seeds)

From what I’ve read seedlings can be satisfied with much less light and a clear humidity dome. That’s alot of watts (and expense) for “just started seeds” but yes you can use it .


Your 400 is going to be a bit short on coverage for a 5x5.
I run a 1000 for a 4x5 area and I’m at the limit with that.
That 400 is good for about 8-10 sq feet.
You have 25 sq feet. You’ll need more to get hard dense nuggets.
For your seedlings you can use some 23 w cfl,s about 4-6 inches above the plants.
@dbrn32 is our local lighting guru and can suggest something that would work a bit better for you for flowering. . :wink::+1::v:


I agree, pretty small light. Wondering what budget would be to get larger light?


Can always add another 2-400w lights or a single 600w when the plants are bigger.


I have grown some autos that didn’t get very big but most autos these days get a decent size 1 plant under a 400 will do nice three would be pushing it

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If I only have 5 total plants at one time, would an 800 be large enough, or should I just go for 1000. And hopefully if I only have 3 plants , 800 or 1000 won’t be too much…would it? Thanks so much for your help.

You’d probably get more even coverage with an additional 400watt lamp. Would you add the 1000w to the existing 400w? Does the current 400w ballast support Metal Halide bulbs?

I’d research the electrical requirements before proceeding, since you might be limited to a certain load unless you put in a new circuit.

What else is on the current outlet/circuit? One circuit can serve multiple outlets, but they all draw from the same limited circuit capacity.

I’m not aware of any 800’s being available? Generally speaking a 600 watt hps good for up to a 4x4 footprint and a 1000 watt hps up to 5x5 footprint.


600 is the best bang for your buck, of the two, 1000 vs 600 watt. The increase in light you get with the 1000 doesn’t equal the extra energy consumption. Just to add more confusion lol


Of course I found this out after I bought the 1000.
But at $250 I couldn’t beat it. :wink::v:


Welllllll worth $250, for sure. I’m still kicking myself in the ass for not finding this forum before buying all my equipment. I had the grow bible, but it was pretty outdated as far as lighting, at the time. I ended up with a 175 watt blurple panel for $300, and the blue side of it (leds, not driver) died after less than 2 years use. I look at what $300 gets you today, and I’m nauseous lol

I thought I was getting the latest and greatest thing. :man_facepalming:


You’re being generous! Last time I looked it suggested epistar were good leds lol.


Aren’t they?

About as cheap and cheaply made as you can get


I have 3 monster clones growing in the tent as well. They are trying to survive. So seedlings and clones in the same 5x5 area…hope its ok.