My lighting question

[Gingerbeard]

Hey.
I'm going to start piecing together my next foray into growing dope. First is a 3x3x6 tent. Second will be the light.
The 3x3 and 2.5x2.5 coverage for veg and bloom I understand. What I don't understand is how deep a light will penetrate. My 350 watt LED is adequate for coverage but, still, I don't know how deep it will penetrate. My max plant height is 24". The colas don't happen that low but the little budicles below do.
Second is the light. With the new tent I'm looking at, perhaps, I'll be able to go 3.5-4', based on an extra 1.5' compared to my 2x3x4.5. How do I know what to look for when it comes to penetration?
This is what I'm considering:

https://www.viparspectra.com/goods.php?id=138

[Guest]

I’m definitely not an expert but that is a pretty small light for that tent. It’s 150w actual. I have 600w in a 4x4 and it doesn’t seem like overkill.

[Farmall]

Can you try to get 50w / sq. Ft.? Or look into the diy strips... I am tickled pink ...as they say

[Gingerbeard]

The 'actual' draw. What does that mean for the amount of light I'm getting on my plants? If I'm looking for 50 w/sf, I would need something larger than a 600 watt LED, which only draws actual 260 watts, for my 6sf space. I've been lighting thinking my 350 was giving me 58.3 p/sf. I have no idea what the actual is.
But what about the depth of the penetration?

The ratings most of the mfgs use for advertised wattage don’t mean anything. The actual wattage draw at the wall is the what you want to know unless it’s a super efficient light.

Gingerbeard you actually have 9sf there so you would need ~450w actual

[gbauto]

LED's are not all the same.
While it looks like it MAY use more efficient diodes compared to the old tech blurples, plan on at least 40 watts/ sq ft of canopy. That's 360 watts to REALLY illuminate your tent. A pair of those fixtures would get you closer.

[DingusKhan]

Have you considered a 315watt CMH? They are optimized for that sized tent, and really do grow nicer buds than other types of lights.

I think you've finished enough grows that you're ready for a "real" light. Have you read Nebula's CMH tutorial? No bullshit. It's the single best upgrade you can make as a new, next-level grower.

https://photos.google.com/photo/AF1QipPxR80rFyx_FxNmZhVqhwJUff07HTtrBktcJ4W4

[Farmall]

Great idea DingusKhan ... the short plants will not require the 12” loss of space at the top of the tent and it is a great great light.

[ZigZag]

Hello Gingerbread, First thing you want to avoid is burning your plants in a space with out much "headroom". If you can't keep your lights at least 20-24" above the canopy when they are at their maximum height_even with LST, topping, etc. then you'll need to consider that more than penetration. You don't want to burn or stress your plants when they are at their peak. You don't want to burn them or cause stress that will delay even trichome development. However if you can maintain enough headroom you should definitely get more light. For the space you could go with DingusKhan's suggestion or get a full spectrum LED. Some manufacturer's make lights that have full spectrum, plus switches to increase blue or red light to enhance early or late growth. With a small tent and more powerful lights you'll also want to make sure your ventilation is adequate to keep your temperatures in the 70-80 F range. CMH will likely put out more heat for the same wattage but powerful LED's can also put out a fair amount of heat and if you need to use a dehumidifier during flowering to keep your humidity down then that will add heat too.
I learned this the hard way, a little more with each grow.

As far as canopy penetration wattage isn't really the best way to determine that, it does influence because more watts usually equal more light when comparing LED's or CMH's among themselves. But penetration can also be relative to the design of the hood on a CMH, and whether or not an LED includes "lens" on some of the LED's that focus their output in a more narrow "beam", providing deeper penetration. But height is very relative too.

As far as coverage is concerned you should look at the PPF and PPFD_ most manufactures now supply that. PPFD is the most accurate measurement of the amount of light spread over the entire canopy_ how even it is from edge to edge_ basically how much fall off occurs at specific distances from the center immediately below the light. Many lights that list a PPF_ say 600_ supply that amount only at the center of coverage and then that can fall off dramatically. Others make lights that are more consistent over a specific area. My grow area is only 4x6' but I have a 9' height so I can keep my lights 18-24 inches above the canopy even when they are 6'. The lights I use are full spectrum LED and the configuration is on a 4x4 frame so the light is spread evenly across the entire 4x4' area. I lose a bit at the ends but not enough to be concerned because I can rotate those planters if I notice a reason to. These lights can also be kept close to the canopy, get great PPF and PPFD for my space and draw only 660 watts. They are pretty spendy but I've done about a dozen grows with them and they are still going strong.

Most lighting manufactures list the PAR for their lights as well but that really only measures the lights efficiency. The PPF refers to how much light is provided at any specific distance (distance is very relative), and is a good measurement of how much light is provided within a specific area directly below the light. PPFD is the best measurement for how consistent the light is over a specific area.
A light that is configured so it puts out more of a "cone" like light_ like a flashlight_will have more drop-off toward the outer margins. The higher the light is over the canopy the more even it is but the less intense.

Most indoor commercial growers I know use very powerful LEDs so they can provide more even light coverage over a large area at a height that won't burn and at the same time draw fewer watts and they also combine those with CMH to get the best of both worlds. But for us who have grow spaces 6' square or less then that's not really an option.

Whichever you decide to go with take into consideration the PAR, PPF and PPFD more than how many watts they draw.
Color spectrum is also an important consideration. For LED's I prefer a full spectrum light that I can boost with blue light during seedling and grow stages and then warm light at flowering.
If you go with CMH then consider getting two bulbs_ one with a cooler color spectrum for seedlings and grow stage and a warmer bulb for flowering.

Apologies for giving you more information than you asked for but I thought I'd just pass this along for you to consider.
Cheers and happy growing!

[ZigZag]

another consideration is that some manufactures offer lights that have dimmable options which can save your plants if they get too tall in a tight space and you start to run out of headroom. Keeping your plants trimmed so the canopy is only 16-24" deep is also a way to increase their efficiency/ penetration.

[SoOrbudgal]

Great tips and information Thanks ZigZag

[ZigZag]

No problem, it took me a while to figure out exactly what and how PAR, PPF and PPFD work in respect to lighting coverage and penetration. I learned a lot from this site, by trial by error and from friends who are master growers for commercial farms. When they explained to me why they had such powerful lights but kept them at least 6' above the canopy it all came together. For them (and most of us) it comes down to budget. If you have to grow indoors then that's a big deal. I don't know anyone growing at home with an unlimited budget. All you can do is research the lighting you decide on and get the best for your grow space that fits within your price range.
PS: I love your "Be nice...."!

[Gingerbeard]

A crapload of information pops up when I don't go online for a day.
For me to get 450 watts of actual draw... a 600 watt, Viparspectra LED draws 260 watts. 132 watts for a 300 watt LED. For my 9 square feet of space, I would need around 1000 watts of LED to get 450 actual draw. I'm still in left field about all this.
I was into computers, for school, a couple years before the Pentium came out. Changes were happening so fast in the industry that I just stopped trying to keep up. What was the best became adequate. What was adequate became a broken pocket watch. I'm there with the lights. I was going to concern myself with PAR, PPF, and all that. It seems like so much more knowledge I would use maybe once, and only talk about it again when my grandkids are sitting on my lap wanting stories about how light used to be.
I've been using a 350 in my 2x3 and would up it to 450 if I weren't considering a new tent. I might keep it simple and just get a 600 watt LED for the new one. HID's are an option I'm going to check out, as well.
CMH's were the first lights I looked at. Not in my price range. I could put together most of a setup with what CMH's go for.

[Gingerbeard]

Then how about something like this? Maybe if I go for 8' tall instead of 6'?

https://www.amazon.com/VIVOSUN-Hydroponic-Light-Cooled-Reflector/dp/B00P8P50G6/ref=asc_df_B00P8P51ZQ/?tag=hyprod-20&linkCode=df0&hvadid=193139379506&hvpos=&hvnetw=g&hvrand=8091237647271468341&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9061245&hvtargid=pla-311013945010&th=1

[SoOrbudgal]

Yep I got the 8ft no more messing around lowering my lights I just raise the pots up higher on risers as needed. Only thing is i'm getting tangled in the opening flap sometimes I think I need a extra arm just to keep from hanging me up?? This won't be a issue for you Gingerbeard. But I sure like the extra space

[Gingerbeard]

Well, hell! The answer was staring me straight in the GWE.

https://www.growweedeasy.com/250w-hps-beginner-tutorial

[Gingerbeard]

The light I was thinking about at the beginning of the post is out. It's not UL or some other acronym certified.

[ZigZag]

[ATTACH]n378827[/ATTACH] Yup, I'd go with the 8' tent for sure. It makes things much easier. Most of the time when I grow different strains at the same time I end up raising some of the planters to keep the same canopy height as the tallest plants. I'm looking for large colas so I train them to be flat but if I have to keep cutting and bending the tall ones so much that I introduce more stress than I think is good for them then raising the shorter ones does the trick very well_and doesn't stress the plants with the most potential. The regular seeds I grow have more of a tendency to hermie than female/auto fem seeds, so too much stress can be a bummer.
I just had one of may smaller plants start to hermie but caught it early and pruned any pods right away every day. had to turn the fans off too so if any pollen did get out it wouldn't blow around. All is good now. plant is being flushed right now and no signs of seed. Others look fine too. It was a gamble keeping it but I had to spend about 30 minuets a day for two weeks checking it out every morning.

As for the lights I would go with something that's at least 450 watts and buy from a manufacturer that provides PAR, PPF at specific distances (should have a chart you can look at), and most important a PPFD "map" that shows how fast the PPF drops off as you move away from the center directly below the light itself.
The best PPFD for veg is 300-600 and for flowering >600 (see attached chart).

For an idea of how PPFD varies at specific heights see the PPFD at different heights chart.
I also attached a pfd on comparing grow lights in case you want more information.

Remember though that these charts are for the lights I have....those made by a different manufacturer will be different.
Look at the PPFD coverage charts in the pdf and you can see how light drops off from the center outwards and how a light bar system or an array of lights
that are close to the size of your grow area provide much more even coverage and penetration.
More questions I'll be happy to help if I can.
Cheers!

[ZigZag]

HUH, well that didn't go as I'd hopped...don't know why the PFD on comparing lights didn't upload. I'll try and fix that asap!

[Gingerbeard]

That's a chart. I understand charts if I know what they represent. This is something I can go with. I already know about the diagrams shown on a lot of product websites. I know, generally, what they represent, but not the importance.
A question about HID's and HP and those. Why is Old Head able to grow his plants past his lights? Like, straight up and leaning real close to the reflector? It seems like there isn't much of a need for distance using one of the HID types. I see the same thing in other grows. Plants getting superclose to lights, Two questions I guess. If the tutorial I linked uses a 250 watt in a 2x4x5, why wouldn't it work in a 3x3x6? I understand the recommended 50w/sf. So why are there good reseults when putting that 250 in 8sf? The 8' might not happen as I don't seem to be able to find one with the 3x3 footprint. Three questions. Last one, I swear.
I'm going to need a minute to go back and forth between your chart and the other diagrams for a better idea. I might print it out. As computer oriented I've been in my life, my brain is low tech. I understand printed media better than what I glean on a computer screen.

Thanks ZZ

[gbauto]

Ginger, I can sense the trouble you're having trying to wrap your head around how much light is enough.
Plants don't give AF about watts, they only care about how MUCH light they get. It's measured in micro-moles of photons.
The wattage metric you keep hearing(50w/sq ft-30w/sq ft) is an easier way to estimate how many umoles of light the fixture can generate.
Current commercially available diodes generate around 2.8umole/watt while older blurple diodes are closer to 1.5umole/watt. That 1.5umole/watt is also the efficacy of most HPS lamps.
It's pretty simple to estimate how much light you'll need to achieve the light intensity you want.
Find the area of your grow space in meters(2) and multiply that value by the desired PPFD(700) level you want to achieve to get the amount of light(PPF).
Ex.: 1 sq meter of canopy x 700umole/m2=700 umolesPPF
If you use a HPS rig, you'll need: 700umoles PPF/1.5 umoles/watt= 467 watts hps
Using current tech diodes- 700 umoles/2.8 umole/watt= 250 watts led