First time grow using sunsystems 315 light 4k veg bulb

my plants have 3 nodes of leaves showing now. i have had the light as far from plants as i could for the last ten days because two of my plants had leaves reaching for the light when i first installed it and it was around 4 ft up. i figured they were reaching because it was too much for the young seedlings. the plants are toward the end of seedling stage and i lowered light 4 inches today.

If any of you experienced guys are using this cmh 315 could you give me a heads up on how far away at different stages you run yours at. i am afraid i am being overly cautious with my spacing.


@Countryboyjvd1971 runs one. Maybe he’s around to comment.

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I use a 55 true watt CFL until my plant is about 8" tall and about 5-7 nodes. So first 2-weeks. Then I bring out the big lights

I keep my light between 24" and 30 for vegg

u use the cmh for your big light? and yes, i am really leaning towards getting a 4 bulb 2ft t5 for germ and seedlings @HornHead thanks!

Yes sir, I have the 315w vivosun 3000k

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I’m using a similar light and through investigating reviews online mine says a distance of about 50cm really pleased with this light system

Try this link. Hopefully it will work. If not, copy and paste to your browser and it should take you there

wow, 19 inches, and that is the 3k light that i’m going to use two of for flowering. good looking light bud. that sounds a little close to me, but as you can tell i’m playing all this a bit on the conservative side. i could see it that close for flowering but not sure i’d want it that close for veg. but i’ve seen your plants and it is working great for you. though there is not that much difference between yours and what hornhead posted @Originalgazelle

I also read that a general rule of thumb is if you can put the back of your hand under the light for a bit and it does not burn your hand that it should be ok. I think the further down that you can get your lights the better the penetration you will get deeper into your plant

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i did some reading before and knew that the phillips is rated best bulb. i read thru the article and i get nothing from the charts, especially the one that had the x’s on it showing par at different heights or something. my brain does not follow what is being shown there.

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@Originalgazelle thanks a bunch for your help. i am weasle ing my light down now. i just moved it another couple inches so have moved it 7 inches so far today. it has kept the same temp in dome by plants so that part is working out good and none of the plants show “reaching” of leaves so i will continue to lower it a bit at a time.

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That’s what I have been doing. Tweak here tweak there.

I think The par connotation in this article refers to how the light is focused within the various 1x1, 2x2, 3x3 etc grow footprint and the amount of light at a specified distance.
Had to investigate this as well.

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