16k lumens HPS vs. CFL

[ceestyle]

Okay, so the point isn't which is "better". I just thought it would be interesting to make a comparison on several fronts.

So some time ago, to deal with temporary constraints on living space, I built this grow box. It measures about 3' x 1.5, give or take. It has core/shell construction, so that it is expandable from 2.5' to nearly 6' in height. This allows moving the lights, while maintaining light seals and the ventilation sucking from the lights.

Shown here is the bottom half of the box, with the spray plastic lining and irrigation shown:



So in the lid of the box, I installed 6x42W CFLs, rated at about 2700 lumen apiece. After vegging for some time, I decided to install a 150W HPS in there as well. Here you can see the lid propped up on the top. You can also see the muffin fans that did a great job of keeping everything cool in the top portion of the box:




So the box worked nice, and I grew some (box-shaped) plants:

Although I had to harvest early, yield and smoke were good.

 

[ceestyle]

So it occurred to me: what effect were the HPS and CFL having on the plants? Which was most important, and what was the ideal height of the box relative to the canopy in order to maximize light use?

This was also initiated by the fact that my canopy got a little toasty in the center if I kept the light too low. My reflector is home made from a sheet of aluminum, so I know it's not great. The whole HPS with reflector cost $60 though, so no complaints.

So I decided to do an experiment to compare the two at various heights. Here are the details:

Equipment:

The systems are rated approximately equally in terms of lumens, although the CFLs pull significantly more power.

System 1:
6 x 42W CFL :: 252W total
3 cool white (at left)
3 warm (at right)
Each bulb rated at 2700 lumens: total lumen rating of ~16200 lumen

System 2:
1 150W HPS
Approximate lumen rating of 16000

Light meter:
Hydrofarm digital footcandle meter

Procedure:

The box top was mounted atop pots over a rug, which served as a map for measuring intensity at various positions. Here is a closer look at the top, and of the setup:

The box top was raised and lowered, to explore a range of heights that one might use to optimize coverage and intensity. The intensity reading in footcandles was measured at many points, by tilting the meter to maximize the intensity reading. This simulates the plant's tendency to turn toward the light. Readings taken with the meter flat showed the same trends, but are not practically relevant.

Results:

CFL Illumination:

Shown below are the intensity maps at the heights indicated on the plots, as measured by the vertical distance from the top of the meter to the edge of the spiral tube (~4,7, and 9"). Note that the vertical color scales are not the same on the first plot as the second two. Purple is 300-400 klux in the first and 150-200 klux in the second.



HPS Illumination:

Shown below are the intensity maps at the heights indicated on the plots (~7,9, and 10.5"), as measured by the vertical distance from the top of the meter to the filament:



Observations:

Optimal height:

Noon sun is 100-150 klux. With this in mind (and my toasted tops at 7"), the lights should be adjusted to a height that keeps the maximum intensity at the canopy at 300-400 or below (purple in the first CFL plot and all HPS plots).

We can see that of the heights sampled, we would choose 4" (or possibly a bit closer) for CFL and 9.5" or possibly a tad closer for HPS. The problem here is that the filament of the HPS is 2" closer to the canopy than the CFL spirals, meaning 4" for CFL means 2" for HPS, and 9.5" for HPS means 11.5" for the CFL. This is obviously a flaw in my design, and an illustration for why this need be considered when designing a system like this.

Coverage:

Assuming we choose the 4" and 9.5" separation for CFL and HPS, respectively, what kind of coverage do we get?

As you would expect when comparing a point source to a distributed source like an array of CFLs, you get much poorer coverage for a flat canopy. From the first plot, you can see that at the same height, the intensity is much more even. As you pull the lights up, the CFL distribution remains relatively even, but weakens quickly as expected. As you pull up the HID, the coverage first gets marginally better - due to the reflector getting more light to smaller angles - and then light quickly weakens with distance.

NB: The crease in the center of the plot is caused in part by the HPS reflector, which very partially obstructs the CFL/light meter line of sight when the lights are about 4" or closer.

In other words, if you want a flat canopy, the CFL setup might work better than a single small HID. On the other hand, this is easily corrected for by arranging plants of differing heights so as to even out distance from the bulb, ala continual harvest SOG.

It also wouldn't hurt to have a more efficient reflector than the approximately parabolic one I constructed. Furthermore, peripheral reflective material will assist in redistributing light in both setups, but more so in the case of CFLs, as the HID light simply does not reach the corners of the measured area.

The main point is that you need to consider the power and location of your lights when designing a grow setup.

The results also further support the fact that lumens DO ADD. If they didn't, what you would get from the CFLs is a constant intensity across the center near the bulbs that decreased as you move away.

 

[skatterman420]

your threads are always so interesting heh, nice research

 

[ceestyle]

your threads are always so interesting heh, nice research

Thanks.

It's what i do, man. If I didn't apply it to growing weed, I wouldn't really be a stoner, now would I?

 

[Muni]

Thanks.

It's what i do, man. If I didn't apply it to growing weed, I wouldn't really be a stoner, now would I?

With proper research like that I'd suspect you of being a white lab coat wearing researcher who catalogs odd things on the weekends for fun. But you'd be making boatloads of cash.

 

[ceestyle]

With proper research like that I'd suspect you of being a white lab coat wearing researcher who catalogs odd things on the weekends for fun. But you'd be making boatloads of cash.

not a fan of the lab coat ... and we all have our hobbies.

 

[Muni]

Very true.

I'd pimp a lab coat. I'm sure people would think all kinds of things about it. It'd be fun at least.

 

[ceestyle]

Very true.

I'd pimp a lab coat. I'm sure people would think all kinds of things about it. It'd be fun at least.

You'd think so, but it gets old pretty much instantly .. once you have to actually do anything in it.

 

[ivanvtec]

great job man. i give you respect for educating people with accurate information. this site needs more people like you who are willing to show people whats really right and wrong by proving it with tests and experiments.

 

[Budda_Luva]

hey ceestyle nice reseacrh i juss got a couple questions does a 150 watt hps fit in a regular light socket???? did the HPS have its own relfector??? if so was the HPS relfector better than the aluminum??? if u didnt have a HPS reflector doesnt that mean the CFL'S were closer the the aluminum than the HPS??? i cant quite put my finger on it but wouldnt that have something to do with the intensity or anytthing since the reflector was in the way it wouldnt really allow for the CANOPY effect from the aluminum as the CFL'S???great, lost my train of thought... uhhh but an other thing like u said yea i could tell that is wasnt balanced cuz u were using books and steros lol shoulda bought suttin like 2 by 4 wood or w/e i unno juss my opinion ughh cant seem to rember any other questions i had but o well but damn GJ im such a fukkin pothead

 

[Budda_Luva]

now that i looks at it i can see why u did alot of this

 

[ceestyle]

hey ceestyle nice reseacrh i juss got a couple questions does a 150 watt hps fit in a regular light socket????

Well, technically yes, it's a regular socket, but you need a ballast, as with any HID.

did the HPS have its own relfector??? if so was the HPS relfector better than the aluminum???

yes, the aluminum was the reflector

if u didnt have a HPS reflector doesnt that mean the CFL'S were closer the the aluminum than the HPS??? i cant quite put my finger on it but wouldnt that have something to do with the intensity or anytthing since the reflector was in the way it wouldnt really allow for the CANOPY effect from the aluminum as the CFL'S???

No, the CFLs were not using the aluminum reflector.

Well, parabolic reflectors DO focus light, but it only enhanced the distribution that you would get from a single light source, which is the main source of that effect.

great, lost my train of thought... uhhh but an other thing like u said yea i could tell that is wasnt balanced cuz u were using books and steros lol shoulda bought suttin like 2 by 4 wood or w/e i unno juss my opinion ughh cant seem to rember any other questions i had but o well but damn GJ im such a fukkin pothead

it was balanced and level, at least within experimental error, I assure you.

 

[GardensGrow]

Kudos on a good experiment with attention to details and possible errors. I think this will come in handy for those doing a cost-benefit ratio of using multiple CFL's over a single HID. While electric cost will be higher with CFL's, yield may make up for that loss due to better spread as shown here by you.

 

[outrunu]

CEESTYLE,

After this experiment, and I know you don't want to turn this into a debate about what is better, but if you could choose one or the other for a small space, which would you use? I started (vegged) with CFL's, but bought the 150 for flower, figuring better coverage for less cost. Appreciate your research and effort to put this together.

 

[ceestyle]

CEESTYLE,

After this experiment, and I know you don't want to turn this into a debate about what is better, but if you could choose one or the other for a small space, which would you use? I started (vegged) with CFL's, but bought the 150 for flower, figuring better coverage for less cost. Appreciate your research and effort to put this together.

Thanks guys.

It's really difficult to comment on that without a side-by-side. The reason that I added the HPS originally was to supplement the light that was already in there, which was sufficient for veg but not nearly what I wanted to flower.

In order to get what I thought was adequate out of just CFLs, it would be very difficult to physically cram that many bulbs in there, and then you have problems with them obstructing one another.

In other words, to compare the CFLs to the HPS is like inadequate light vs. inadequate light.

If I were forced to choose, I would probably opt for the CFLs, just because of the coverage. All the mylar in there helps them more as well, as the HPS would simply not reach the corners. A better reflector could certainly help with that, but unless you tailor your canopy with smaller, different sized plants - to even out the distance from the bulb - you're going to have part of your space that is suffering somewhat.

All of the above is based on the cabinet of 3 x 1.5'. A smaller space, say 1.5 x 1.5, would be a different story. There, you would probably go for the HPS.

 

[outrunu]

I'm in 2x1.5. I really think this HPS is just awesome for a cab this size. I originally wanted to flower 1-2 plants, starting 3 but got 3 ladies, so I am a little crammed but its seems to be ok. I was able to get 12 CFL'Sin my box. I used a shelf that was adjustable that it came with, a vanity and Y's. Since I have the setup I may try just cfl's next time as a comparison, but thats still a ways off. Theres photos of the setup in my journal if your at all interested, and here's a pic of the box with the HPS. Been great pickin your brain!

(BTW +rep when it lets me, I apparently haven't spread enough around...lol)

 

[Lizard.King]

for all your lighting needs

Although I'm still kind of a new poster, I keep seeing a lot of the same comments--many of which are answered an Dr. Khronik's excellent El Cheapo Guide to Lighting. But there are a few things I'd like to add in regard to watts, lumens, cfl, hps, and efficiency and how much light you need. Maybe this should be stickied?

Watts have nothing to do with light or growth. Watts measure how much power a light fixture uses to produce light. You can tell how efficient a light bulb is by looking at watts. A 23 watt CFL produces as much light as a 100 watt incandescent...even though the incandescent has more watts, it's useless. See what I mean?

What you care about is light...more specifically, light energy. That's what plants use during photosynthesis/growth. Light is measured in lumens. In my experience and reading, lumen amounts per sq. ft./sq. m. look like this

2000 lumens sq. ft./21500 lumens sq. m. = Absolute minimum for growth. You won't get much from this, especially after the plant has grown a bit. Not really enough to flower well.

3000 lumens sq. ft./32250 lumens sq. m. = Pretty Good growth. Enough light for the entire light cycle, although your yields may be lower.
4000 lumens sq. ft./43000 lumens sq. m. = Very good growth. Once you pass around 3500, growth rate and ability goes up fast.

Over 5000 lumens sq. ft./53750 lumens sq. m. = Optimal growth. Dense growth in all stages.

Keep in mind that using reflectors, using mylar or having flat white walls, and keeping your lights close to your plants keep you from wasting lumens. It's not just about having light, it's about getting the light to your plants. IMO, people ofter overbuy lights. This creates more light, but the light isn't always hitting the plants. And that creates more heat and ventilation issues, which causes stress problems.

That's why it's still impossible to tell anything about growth or yield based on just lumens. A guy that has an HPS that is too far away from plants that have no walls near them and no ventilation may get poorer results than a grower with CFLs that uses reflectors and has a couple of lights under the canopy in a well-ventilated spot.

HPS lights are often said to generate more heat than CFLs. That's not really true...it's just that they are more efficient at producing light, and there's a smaller surface area on the bulb itself for the resulting heat to dissipate. That means more ventilation. But the higher amount of lumens per watt means you use less power and get greater light penetration through your canopy. Still, I'm a believer that well used CFL's can give you great grows with less ventilation and heat issues. If you're in a small to very small area (less than 4 sq. ft./.25 sq. m.), I'd consider the advantages of CFLs in that way.

But HPS is more efficient. A typical 250 watt HPS bulb/unit will produce about 27,000 lumens. I've seen people use a 250w in a 3' x 3' room and get good results. That's 9 sq. ft. which = 3000 lumens a sq. ft. (Really, a 250w HPS is better in a smaller area.) to give you an idea of the difference in efficiency of CFL vs. HPS, think of this.

23w CFL = 1600 lumens = 69.6 lumens/watt
30w CFL = 2000 lumens = 66.7 lumens/watt
40w CFL = 2600 lumens = 66.3 lumens/watt

compared to

150w HPS = 14000 lumens = 93.3 lumens/watt
250w HPS = 28000 lumens = 112 lumens/watt
400w HPS = 50000 lumens = 125 lumens/watt
600w HPS = 90000 lumens = 150 lumens/watt

So you can see that HPS is more efficient than CFL...and as you get into bigger HPS bulbs, it becomes a lot more efficient. There's also fewer hassles with multiple cords and saved money on your energy bill. If you've got a big area and/or you can deal with the heat and ventilation, HPS is the way to go in flowering. Still, I'm a believer in small HPS lights and combo HPS/CFL grows...if you've got a 2' x 2' room, you can use a 150w HPS and 4 23w CFLs from Wal-Mart and get a terrific grow with very few heat issues.

Taken off of

Answers about CFL, HPS, How Much Light... - Cannabis.com Forums Message Boards - Medical Marijuana, Cannabis Club, Dispensary, News

 

[moon47usaco]

Thanks.

It's what i do, man. If I didn't apply it to growing weed, I wouldn't really be a stoner, now would I?

You are a lighting designer... ??

Any way you flip it it is kool info... =]

Thanks...

 

[ceestyle]

You are a lighting designer... ??

Any way you flip it it is kool info... =]

Thanks...

haha .. no, i'm a scientist.

 

[moon47usaco]

haha .. no, i'm a scientist.

Of what field if i may ask... =]

2000 lumens sq. ft./21500 lumens sq. m. = Absolute minimum for growth. You won't get much from this, especially after the plant has grown a bit. Not really enough to flower well.

3000 lumens sq. ft./32250 lumens sq. m. = Pretty Good growth. Enough light for the entire light cycle, although your yields may be lower.
4000 lumens sq. ft./43000 lumens sq. m. = Very good growth. Once you pass around 3500, growth rate and ability goes up fast.

Over 5000 lumens sq. ft./53750 lumens sq. m. = Optimal growth. Dense growth in all stages.

Should that be lumens per cubic foot/cubic meter... ??

How would you get the square feet of a three dimensional growing area...??