Are my lights efficient for my space?

Hey there! Just looking for opinions and what other people are growing with ? grow space is 5x8 and im running 2 x 400 watt hps about 1.5’ apart! Is this efficient for 4 plants or can i do more (which id like to)? I Only grow autos

Sounds like you’re doing great for the space.

No and yes i have 2 600w mh and hps in a 4x4x6 grow tent and getting great results.
No because at 50watt a square foot you need 2000 watt to use the whole space

Yes because a 400 can handle 2 plants and your only growing 4 but the difference will be how big you are trying to grow them out is where you will need more lighting

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Keyword here for this grow is autoflower. I flowered and vegged my autoflower with less than maximum wattage in my tent and it seemed to do fine. That’s all this persons grows, so I think they’ll be okay. What say you @dbrn32 ?

But he also said i want to do more

If they do want to expand, yes more light is needed. You’re right.
I think @Kroncaddycustoms would do well if they could spread the light out a little more.


I usually say there’s no standard across different lights that equates to par levels per watt. Some lights take a lot of energy to hit recommended par levels, and others can do it with significantly lower power. That probably applies more than anything.

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Wow all the feedback so quick is awsome @Covertgrowe @dbrn32 @ThcinKC…i do great with what im doing but a few more would be nice, maybe add another 400 hps lol or bite the bullet and switch over to led lighting maybe cheaper in the end? But will it be as good as HPS?

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1- 1200 watt LED off i got for $44
Now its $88.
Works good. Im just vegging indoors and planting outdoors in spring in a dog cage but if i was going to flower them indoors what i would think about is HOW CLOSE CAN YOU KEEP THE LIGHT BEFORE IT BURNS/BLEACHES YOUR LEAVES?
The closer you can keep the light the more efficient theyre used but less surface area covered. I try to say 100 watts per sqaure foot of floor. You could flower with 20 25 watt CFLs shovved close to the plant and to me its equal or better than a HPS because you got 20 bulbs 2 inches away all over the top. Up close and intense. Plus if you LST and keep ur plants short the Top buds get equal light as the bottom.

It depends heavily on what you consider better and cheaper. There are a lot of leds available that will run higher efficacy than hps. There are also differences in light spectrum between led and hps.

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Can you remove Walmart link please. They’re not on approved list of vendors to link. If the same product is available on Amazon, dealzer, or aliexpress you’re welcome to link from there. Otherwise a screenshot would be acceptable too.

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if u do go LED, i suggest HLG QB, they r the best lights for the money right now,
260-270 watts of QB will replace a 400w HPS and will do as good or better then the HPS.!!
if u r adding QB to the HPS i’d suggest HLG 260w XL with 4000k V2 boards,
from GrowersLights .com.!

being able to light the same area with less watts means less heat created,
less created means less cooling needed.!
if u replaced your 2x 400w HPS (800w) with 2x 260w QB (520w) u would have 280w of less heat to deal with,
this is why i swapped from 400w HID to 135w QB’s and my plants love them.!!





So as ive been looking just quick into led lights im confused…there some led lights that are 2000watt but only pull 190 watt from the wall! If i had 2 of these 2000 watt led it should replace my 2x 400watt hps and give me more then enough light? Wow this can get real technical

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Yes, this is confusing. They say it’s equivalent, but it isn’t. @dbrn32 is better at explaining it than I am. @Kroncaddycustoms

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I have 2 tents 4×4×80 1 has viperspectra 600 w and a vivosun 600 w other has 1350 viperspectra huge footprint i got 4 gsce in1 and 1gdpurp 1 dr b banner 2 gsce in other 2 months in also got 2 autos 2 weeks old under t5 lights that they love , 2 more weeks and they all r going 12 /12 those gsce from i❤gm r incredible 2 of them r so monster i cant wait to see them bud

Trying to pay attention to watts is difficult and nearly meaningless with leds. Cheap leds aren’t anymore efficient than hps despite what some of the manufacturers try to tell you. Good leds can be a lot more efficient than hps. In a perfect world every light manufacturer would give us an accurate total flux for each light, then we could decide which light to buy based on our desired light intensity. They don’t, so we’re kinda stuck with either light manufacturers that do or rough guesstimate based on lumping them together.

In a 40 square foot space, you could probably go as big as two 1000 watt hps lights. Two 600’s would be ok, but it would be a fairly expensive space to light with good leds. Using looking at about $700 per 4x4 to start.


@dbrn32 Dang you think 2 x 1000 watt hps would be alright in my 5x8 space? My ceiling is 7’…

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Well, I’m saying light intensity wise they would be anyways. You would probably want to go with air cooled setups to help maintain temps. But ya 20 square feet is really about ideal for 1000 watt hps.

Duuuuude! This is amazing! Maybe this is why my yeilds are mediocre with 2 x 400hps…im going to ditch them and buy a couple 1000 Watters! Its gotta help, there is no temperature issues as its in the besment with heat during winter and a/c in the summer wooooooooo

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Copy that. If you can maintain canopy temps without them, no problem.