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Which grow lights for Lowest heat!?

Oceanicnomad

New member
I'm struggling comparing all the options available today and what would be best in my situation.

I have a Veg room that's 10x10x7.5 and currently run 4 x 1000w MH in adjustawings. 41 plants in 7gals. Room is air-cooled by only an 8" vortex fan, this also heats my home. However I have to run at 75% or I'll burn the tops, stunt them, and it gets too hot. I also have big problems with long internode spacing, especially compared to others I've seen under t5s.. Summer is around the corner and I know I'll need less heat so I don't have to run the central AC again all summer. (I can't afford the power upgrade for another AC)

So... Should I get cool tubes/magnum reflectors which would run about $2000 with a new fan.
Or... Could should I utilize the new technology keeping in mind this is veg only...
I was thinking 6x315watt cmh... Or some cheaper (mars) led's? I'm not sure what else is out there that'd be close to 750-1000W MH? Keep in mind I only have 7.5 ceiling height and want them a good 4ft or chest height before I flip to my vertical room.

So my main objective is to shorten those damn internodes and remove a significant amount of heat, power savings secondary but a big bonus. Budget is around 2k

Thank you for your help!
 

FunkBomb

Power Armor rules
Veteran
Your only options are CMH and T5. You could go the LED route but you'd go way over budget. You would save money over time because of the efficiency of the diodes and much less air conditioning.

There are LED replacement bulbs for T5 that would work for you. Anything 4000 kelvin and higher would fix that internode spacing issue you're having.

-Funk
 

herbgreen

Active member
Veteran
I think you answered your own question T5s

T5 units are good solid option for veg plants

LEDs would be no heat if you can find the right spectrum and amount of wattage for your needs

T5s are a no brainer and bring some heat into the room plants need

Got to watch out led manufacturers like to list watts as "equivalent to whatever"

You will need to unscramble the equivalent watts to actual watts to amount of light your plants really need

led is measured also by its ideal output in an perfectly cooled environment which it will never be in so you need to kind of ballpark it

And you probably need close to the same watts as T5s

There are some diy threads around here where these guys manage to squeeze some serious performance out of little watts but if you have a room like that you may want some thing sure to be enough for your plants and electrically url approved for damp spaces

combo of led 5000k and T5s would be good way to go....leds really tighten up inter nodes
 
I agree with iBogart on that one. Use adjusts with CMH and oscilating fans under the reflectors to direct the heat towards your ventilation.
 

Oceanicnomad

New member
Wow thanks guys. I really like that CMH conversion kit! But will I have the footprint for an 8x8 or 9x9 space? I thought each one covered a 3x3 in which case I'd need like 9? I do have a few more reflectors...
I had also considered a chinese 630W double bulb CMH so I could just run 4... But not sure how many btus of heat that leaves me with in comparison.

I do run those big fat 6500K 1000w right now but I just can't slam them with enough light/close enough due to heat.
Would the t5s have enough penetration with a 4ft+ plant? I'm vegging 8 weeks after transplant from solo cups. I'd also need 8 of the 2x4ft fixtures at $350 a pop, which again heat.. and makes air cooled mh cheaper. But those t5s are just so Damm tight! The difference in bud size/density is quite noticeable in my flower room.

So LEDs just aren't worth it unless top of the line eh? They cost about 2k a pop up here which is why I discounted them. Maybe once I'm more established and can see the longevity of it. Comparing them is a huge headache.

Im leaning toward cmh but unsure of the coverage and if the 315 is enough light.
Cheers! :thank you:
 

iBogart

Active member
Veteran
Wow thanks guys. I really like that CMH conversion kit! But will I have the footprint for an 8x8 or 9x9 space? I thought each one covered a 3x3 in which case I'd need like 9? I do have a few more reflectors...
I had also considered a chinese 630W double bulb CMH so I could just run 4... But not sure how many btus of heat that leaves me with in comparison.

I do run those big fat 6500K 1000w right now but I just can't slam them with enough light/close enough due to heat.
Would the t5s have enough penetration with a 4ft+ plant? I'm vegging 8 weeks after transplant from solo cups. I'd also need 8 of the 2x4ft fixtures at $350 a pop, which again heat.. and makes air cooled mh cheaper. But those t5s are just so Damm tight! The difference in bud size/density is quite noticeable in my flower room.

So LEDs just aren't worth it unless top of the line eh? They cost about 2k a pop up here which is why I discounted them. Maybe once I'm more established and see the longevity of it. Comparing them is a huge headache.

Im leaning toward cmh but unsure of the coverage and if the 315 is enough light.
Cheers! :thank you:

3x3 for flower on the CMH. I think you could go with a larger footprint for veg. Say a 4x4. I'd say shoot for 20k lux or higher and that would be premium veg lighting with CMH. You can't beat the cost with those kits though, even if you needed to add a couple extra lights.
 

Drop That Sound

Well-known member
The smaller 2 or 4 bulb t5 fixtures, supplemented with rows of cheap 75-100watt equivalent screw in LED bulbs in between them, 3000-5000k mix.

You could even mount the bulb socket bases (cheap ones on ebay) right along each side the t5 fixture housings on a strip of wood, and wire them in to the t5s as well.

I'm basically using the same combo right now and the plants love it. 315w and up CMH or MH bulbs with their single points of light just don't compare IMO, especially if you are spreading the plants out and heavily training.

I've thought about building fixtures with multiple smaller CMH bulbs, 50-100 watters, just like DIY COB setups. You could save tons of energy by turning off some of the bulbs when needed, and get them way closer.
 

herbgreen

Active member
Veteran
There are LED replacement bulbs for T5 that would work for you. Anything 4000 kelvin and higher would fix that internode spacing issue you're having.

-Funk

These t5 replacement LED tubes fit right into a T5 socket and thats a very cheap easy way to combine LED/t-5 every other bulb on 4 or 8 bulb t-5 unit

LED tubes run about 1/2 the watts as the t-5 and no heat be good in the mix

The 8 bulb t-5s are 400watts and mix led tubes in cuts it to 300watts these bigger T-5s have a very powerful effect

Thanks for linking the cmh adapter/ballasts would work really great w/air-cooled reflectors!
 

Drop That Sound

Well-known member
But when your buying that many t-5 fixtures, that come with bulbs already (unless you can find ones that don't for cheaper or youll be stuck with all those tubes), it would cost a fortune to replace all the bulbs with LED tubes.

I am going to replace the t5s with those LED tubes in my 8 lamp though , but only as they go bad, and because its too wide a fixture to fit the much cheaper screw-in bulbs on the side, in my small veg room anyway.

For sure though, T-5s + LED (and maybe a few 315 CMH's on the side) for the win!
 

Itsmychoice

Well-known member
ICMag Donor
315s

315s

I know it might be late but the single vertical bulb 315 fixtures with the ballasts remotely mounted out of the room are unbeatable. I do 6 over a 8x14 for veg. Hang them about 4' over the canopy and you will grow bushes. In flower it's 2.5x2.5' about 2' over the tops. I think veg is probably closer to 5x5. The 3100 bulbs seem to make them a little less stretchy. I mix the 3100 and the 4200k in veg for that reason. 3100 on the ones just out of the cloner and the ones in the biggest containers. 4200 for the middle. It works for my set and supplies for 12k flower. The cloner prefers a single bulb t5. T5 is hard to beat for plants less than 1' tall but after that they just don't have the penetration.
 

zachrockbadenof

Well-known member
Veteran
last grow in a 4x3.5ft tent we used '2' 315 cmh's bought off ebay- 4plants grown.. thought the buds were airy, think the light was insuff. this time adding side led lighting-
 

Itsmychoice

Well-known member
ICMag Donor
In flower

In flower

Running plants off the same mother and on the same resivoir the plants under the cmh look better and are denser than the ones under double ended hps. That's in different rooms with several runs. Hanging a bare 315 bulb in the aisle and the plants closest to the bulb are always the winners. There are pics here. https://www.icmag.com/ic/showthread.php?t=350368

The downside is mounting 3 times the fixtures. If I were to outfit a big room again it would have 4 315s every 6x6.
 

Easy7

Active member
Veteran
A watt puts out 3.41 BTU no-matter the system. So it comes down to spectrum. CMH and LED put out 'better' or more specific spectrum, thus the theory is they require less watts for desired performance.

I doubt there is a lot of difference between ceramic metal halide and metal halide. Ceramic insulators simply last longer. The spectrum's are a bit different, not a lot.

The only way to create less heat, is to use less watts. That goes for everything in the room. Not just lights but also all the other equipment. Add all the watts for everything and multiply it all by 3.41 and you have the BTU being produced. Venting outside is a huge plus.
 

Oceanicnomad

New member
I know it might be late but the single vertical bulb 315 fixtures with the ballasts remotely mounted out of the room are unbeatable. I do 6 over a 8x14 for veg. Hang them about 4' over the canopy and you will grow bushes. In flower it's 2.5x2.5' about 2' over the tops. I think veg is probably closer to 5x5. The 3100 bulbs seem to make them a little less stretchy. I mix the 3100 and the 4200k in veg for that reason. 3100 on the ones just out of the cloner and the ones in the biggest containers. 4200 for the middle. It works for my set and supplies for 12k flower. The cloner prefers a single bulb t5. T5 is hard to beat for plants less than 1' tall but after that they just don't have the penetration.

So 4ft over the plants and the light is still intense enough for tight nodes? I've been trying to get them as close as possible without burning but its a pretty small footprint. And I'm still not sold that the nodes are any tighter unless directly underneath.

I bought 2 of the 315cmh with vertical bulb hoods. It allowed me to turn the other two 1k MH up to 100% and holds my temperature at a perfect 75 (down from 81)

The MH are still too hot at the canopy without ac to get close enough to prevent stretching though, so looking at upgrading all 4 reflectors with the conversion kits and running six 315s in the 10x10 room. Bit of an awkward pattern.. and with 1,800 watts I'll probably be a little low on heat come winter if 2,600 watts holds it perfectly right now.

I guess im still a bit confused as some people say 315s are the ultimate veg light. Others are saying a watt is a watt.. If the spectrum is twice as good, so a 315w cmh=600w MH would it be safe to assume my 1,800 watts of cmh will give me enough light to almost match 4,000w of MH?

I'm thinking about getting one or two t5s for the side and I could just rotate plants underneath each time I water to help stack some nodes at the top. I'd love to run all t5s but it sounds like they won't penetrate enough for a 3-4ft plant and it just seems like a ton of lights to deal with.
 
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