Single light vs multiple light source

[GreenThumb14]

So I'm trying to decide if it is better to use a single 400w to cover a 3x3' area or 4x 100w or 3x150w bulbs for a scrog grow.

I know that the 400w will be more intense, however the light is being emanated from a single source (arc tube) and the object below will be most intensely lit compared to any other spot as the distance increases. This includes any light that is reflected - sometimes multiple times before leaving the reflector.

With multiple bulbs evenly spaced or even doing a cross + style mounting in the reflector would break the scrog down in to 4 sections each with it's own light source. The light would travel less and therefore be more intense by the time it reached the canopy.

That's just my thoughts on it.

Pro's and con's?
I'm wondering if multiple bulbs would generate more heat than the single bulb.
I'm using CMH and <150w e-ballasts are readily available for $100 or less, so waste would probably be equal to a single 400w mag ballast.

Does anyone have some first hand experience to share?

 

[MMAjay420]

im no pro but im thinking you will be best suited with the 1 400w light.....

 

[GMT]

3x3 it would be pretty hard to fit more than 1 bulb reflector in there unless you went cfl. Personally I'd stick to a 400w hps, with reflective walls you wont suffer or regret it but heat will be a prob without decent airflow

 

[GreenThumb14]

All the bulbs would be in the same reflector... It's large enough and the bulbs are only 5" long, so they could be arranged many different ways.

 

[Hammerhead]

for such a small space I would stay with 1 400. All of the other config wont have much penetration.. If your doing Lollipops the 3 150 might work OK. Thats still allot of stuff for the same results. 400 is your best option IMO..

 

[GreenThumb14]

for such a small space I would stay with 1 400. All of the other config wont have much penetration.. If your doing Lollipops the 3 150 might work OK. Thats still allot of stuff for the same results. 400 is your best option IMO..

My reasoning is that I would be able to use 150w e-ballasts with 150w cmh bulbs. If I go to 1 400w cmh I would need to run a mag ballast. Cost wise I'd spend about additional $150-$170.

One thing I was thinking is that since I am running 2 separate grow spaces, one has a 250w cmh in it on a digi ballast and I want to add another 150w cmh with eballast.
The other grow space I could do a mag ballast with single 400w cmh. Both sides are growing the same strain, everything is identical. Only diff would be the lighting.

Wouldn't be too difficult to sell a 400w mag ballast if I didn't like it and they're only around a $100 anyway.

Would be a good test to see multi bulb over single and magnetic to digital/electronic.

 

[Hammerhead]

400hps mag ballest are cheap. I can build a 400 for about 75$..MH would be even cheaper..

 

[huligun]

Here is how my spare bathroom is being put together.

 

[GreenThumb14]

Crunching the #'s gives me more lumens and more wattage per sq/ft if I use the 3x 150w over the single 400w

 

[xmobotx]

dont forget efficiency{the 400 is more efficient than the 150 anyway} by the time you factor in loss from multiple ballasts compared to 1; diminishing returns will likely be the un-doing of the multiple point source plan

any potential gain is also offset by the additional complication

 

[GreenThumb14]

The 150w eballasts use 160w... So 3 of them would amount to 30w of waste for 450w of lighting... A 400w mag ballast has an input of 465w... So for only 15w more (480w total) I'd get an extra 50w of lighting. 9sq/ft , so that is 3sq/ft per 150w bulb and 50w sq/ft. 400w single would be 44w sq/ft. The initial rating on the 400w cmh is 33,800lm... The initial rating on the 150w is 14,000lm. 33,800 / 9 = 3,755lm sq/ft. 14,000 / 3 = 4,666lm sq/ft.

Let's not forget the inverse square law. By the distance the light emitted from the 400w arc tube bounces around to illuminate the other side of the reflector and then down to that side of the plant, the light has traveled a significant distance = a lot less light intensity, on the order of at least 1/4 if not 1/8 or more. So ya, directly under the arc tube there will be great veg growth and fat buds, but not so much around the edges of the scrog.

More lumens and watts per sq/ft and multiple light sources = no place in the shade. Less waste for more total light wattage over the 400w mag ballast = less heat generated from equipment.

The hottest point is directly under the arc tube... The 250w and 400w cmh's are the same length, so that spot would get even hotter meaning I'd have to keep the reflector up higher, where as 3 150w bulbs would put off less heat and allow me to keep the reflector lower.

 

[xmobotx]

makes sense to me then

i would anticipate the better distributed light to be 'worth the gain' so long as efficiency isnt compromised

perhaps the efficiency thing kicks in @ the 1000 watt level w/ HID

so the only drawback now is the wiring burden/wiring{and cooling}logistics to 3 lights vs 1

 

[GreenThumb14]

It'll be in an air cooled hood... I'll mount the bulbs from the center point of the hood in a triangle configuration. Wiring isn't a big deal, just 3 separate 2 conductor wires.

These are the ballasts...
http://www.ballastshop.com/72c5482np.html

Easy enough to mount on to a hunk of aluminum for passive cooling.

The 400w cmh is 84.5lm/w initially, the 150w is 93.3w/lm initially. It'll stay at that output a lot longer on an electronic ballast than the 400w on a mag ballast. The only downside is the extra components/wiring. The bulbs are only around $20/ea and they use medium style sockets and I know that the local hardware store sells ceramic medium sockets with mounting tabs.

It's going to cost a little more with the initial setup but instead of wasting 65w to heat with the mag ballast I am able to turn that in to more light. All in all I think that multiple light sources with electronic ballasts over a single 400w on a mag ballast is the way to go and I've been researching this half the damn day lol.

Ya the single 400w will be more intense but that light still has to be reflected around to get to the other side of the plant... It can't just magically shoot through the leaves lol. I do know that this does happen but not with much intensity at all. With 3 light sources there will basically be little space that isn't exposed to higher intensity lighting.

 

[pip313]

Intense is a made up phrase like inverse square is wrong (for growing) and so is lumens. Ceramic metal halide is the shit (high par) and if they ran at 1000w and digital I'd have em. Did have one the 400 that bastard gave my right hand a sun burn (hand that worked in closet). My point is if you want to pay the extra then do it mixed spectrum for sure.

I use the word intense too but it's still wrong it doesn't describe anything. Par lumens they measure something intense is subjective.

 

[FRIENDinDEED]

ONE LIGHT = ONE PROBLEM

MANY LIGHTS = MANY PROBLEMS

 

[pip313]

That could be good or bad though, one bulb one bulb dies or three bulbs one bulb dies?

 

[GreenThumb14]

The only advantage I can see with a single 400w bulb so far is that it's easier to setup and half the price because of buying one mag ballast instead of 3 eHID ballasts... 3x 150w CMH bulbs is right around the same price as buying 1 400w cmh bulb. I hate the idea of using a mag ballast for some reason... Oh ya, because it wastes 65w of power that I could be turning in to additional light.

Intense is a made up phrase like inverse square is wrong (for growing) and so is lumens. Ceramic metal halide is the shit (high par) and if they ran at 1000w and digital I'd have em. Did have one the 400 that bastard gave my right hand a sun burn (hand that worked in closet). My point is if you want to pay the extra then do it mixed spectrum for sure.

I use the word intense too but it's still wrong it doesn't describe anything. Par lumens they measure something intense is subjective.

Care to elaborate on any of this? Why is "intense" a made up phrase and why is inverse square wrong for growing? I understand the marketing gimmick with lumens... What is your actual opinion of using 3x 150w bulbs consuming 480w of total power (including ballasts) over 1x 400w consuming 465w on mag ballast? Regardless of the price differences... Only talking about how well the light will be distributed and how the grow will be over the two options. I'm looking to get the most yield for input... Not concerned with the hour or two it will take to setup 3 sockets in a reflector or the price difference.

 

[Jnugg]

I don't see 3 bulbs in one reflector being any different than one 400 in a reflector...if you want even light spread with multiple points/sources of light it is best to have each bulb in it's own reflector.

My vote is 1x 400w HPS in a large a/c hood...or yiu could try vertical bare bulb with plants in a circle around the bulb or one plant per wall tied back...

My 400w HPS bare bulb vert in a 3x3 tent,just to give you some thought.

Check out my vert album if this tickles your fancy.

 

[Easy7]

More ballasts are just making things to complicated.............I'd go 600~!

 

[GreenThumb14]

More ballasts are just making things to complicated.............I'd go 600~!

I know what I'm doing... Wiring up ballasts isn't rocket science. I can't use a 600w because there are no 600w cmh's available.

I don't see 3 bulbs in one reflector being any different than one 400 in a reflector...if you want even light spread with multiple points/sources of light it is best to have each bulb in it's own reflector.

My vote is 1x 400w HPS in a large a/c hood...or yiu could try vertical bare bulb with plants in a circle around the bulb or one plant per wall tied back...

My 400w HPS bare bulb vert in a 3x3 tent,just to give you some thought.
View Image

Check out my vert album if this tickles your fancy.

The same reflector was my concern as well. If I wasn't in a 3x3 tent, I would do multiple reflectors. It's the biggest reason I have to use a single 400w.
However, I'm still stuck with the thought that the 400w ballast is drawing 465w, whereas with the 3x 150w bulbs on eHIDs I'd be pulling 480 but getting 450w of actual light.
Despite being in the same reflector it's still more light. I'd have 50w sq/ft if I use the 3 separate bulbs.

I really really wish I could find an affordable 400w digital low freq ballast... The 250w from Accendo is there largest unit currently and I paid $212 + $45 customs and $25 shipping, ow my balls!
The Ceramatek 375w kit is like $600... Even the 315w kit is $500. Gets something like 115lm/w, though.

If I string 3x 150w Philips Advance electronic ballasts together it costs me $250 shipped and 3 bulbs would be $67 shipped.