Question about CMH/LEC/CDM

I was currently looking into making this switch and upon shopping for the ballast and bulb and what not… I came across this

My question is… Since the ballast is attached to the bulb and hood… doesn’t that just create more heat in your tent? Does anyone use these type and can let me know how they work?

Thx :slight_smile:

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I use one by sunlight supply… Plants love it… Does produce a bit of heat since ballast is attached and their is no glass on hood to hold heat away from plants. But I know they do make one with a glass hood that can be vented and the ballast comes in built in or separate. But the one I have is just base model they retail at 559$, so the upgraded versions are lil more I think. Overall great light. The one your looking at looks like a good one as well…


Thanks @Dr.DankThumb420 … I already am having a lil heat issue somewhat…so was just looking for other alternatives and I have heard great things about these lights, as far as the actual grow goes… not to mention my electric bill would like it better Im thinking… Thanks for your input :slight_smile:

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@Donaldj use lec lights I believe and can be a good resource for you in that department also @peachfuzz is knowledgeable on those type of lights I myself am a led grower strictly and have never used anything other
Happy growing :v::cowboy_hat_face:CB

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@Countryboyjvd1971 Well I am trying to decide between LED and CMH/LEC or whatever they are called… so I might pick ya brain about LEDS too at some point lol


Feel free @AngelicSoul
I use leds cause of the heat issue with other types and the technology is only getting better
I’ll say this get full spectrum leds and you’ll be happy
If you have questions tag me if I can’t anyit I’ll get the right person to help out :+1:


@AngelicSoul I should be modifying a diy cob build this weekend if components show up in time. I didn’t plan on doing a tutorial or anything, as that info is readily available via YouTube or plenty of other places. But I’ll put some pics and general info up. If that’s something within your means, I’d be happy help in any way possible.


No wayy, you should definitely do a video for us, I know I would LOVE to watch it! Specially if you could dumb it down for someone like me lol! I want to build my own one day, and I’ve watched other videos, but I would much rather watch a forum members video honestly. If not, no worries!!



To be honest, I would do a video if I thought it would help haha. There’s absolutely no way I have the tech, time, or knowledge to be anywhere near as thorough as the better videos already available. I have an electrical background, but more in automation and controls than like say a residential electrician. And I’m very familiar with the components due to a couple of work projects.

I’m not a great teacher, but I have no problem at all answering questions or helping with anything. So whenever you’re ready feel free to hit me up. The components are getting very easy to work with. If you’ve wired a fan, made/repaired an extension cord, or anything along those lines I’m pretty sure you could do it. Yet I completely understand how it could be intimidating.

I built a 4 cob fixture for 2x4 a little while back for a friend. It was extreme budget build and lacking some coverage. He had a little extra cash and wanted to upgrade it a little. So we’re gonna replace some older vero cob’s with newer vero 29se, and add 4 bridgelux strips. His 200 watt fixture should pull about 440 watts and fix his coverage issue when I’m done.

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If you’re already having heat issues you might want to look into LEDs a little bit more… not that I use LEDs… but I jump through hoops in order to get the heat down in my flower room because I run XXXXL hoods with 600 watt magnetic ballast with hps bulbs and it was no easy task to get temps dialed in… :wink:
But as to your question… I would not suggest a hood with an attached ballast… way too much heat … my ballasts are in a different room then my hoods… that’s the only way to go… lamps make enough heat as it is… :wink:
In the end after you do all your research on the LEDs if you’re still interested in running an HPS or MH set up , hit me up and we will go over the parameters of your grow and your room and what your plans are and see what we can get figured out for you that will be reasonably priced… :wink:

:v: :sunglasses:


I’m with @ktreez420 you should do a tutorial video or still I’m cool either way
I’m sure it would be a big hit actually brother
I know I’ve been in discussions on a few threads about doing just this type of thing as well as building from scratch as I know @ktreez420 has beeen as well
Tag me when you post what ever it is you decided to do @dbrn32 I like the sound of it lol


I love LEC’s at 315w using nice digital ballasts I run 3 and as for heat no problem get less heat than running 400w or 600w HID hands down with one exhaust fan I can bring temps right down to ambient in a matter of a few minutes. The plants always look like they are in a photo shoot under them leafs stay green longer during flower. No bugs in my flower room ;Pthey hate it


My current set up is a 4x4 tent that right now has my babies in it under t5…'that tent holds at 75-77 degrees…

I also have a 8x4 tent that has my flowering girls in it now…temps stay about 86 :confused: so I added a exhale bag…but that is running two 600w hps cool tubes…with a 10" exhaust…

Both my tents are in the basement and my house is ac cooled so basement stays hoodie cold for me at least…

I am about to harvest my 8x4 … But my 4x4 are babies (two weeks from seed) and I want to make my switch in my 4x4 tent first then figure out my 8x4… I was already told my 4x4 would need four 300w leds so I was looking at mars hydro… And my 8x4 I have no idea…

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Thinking out of the box here, but have you considered some led replacement tubes for your 4x4?

It probably won’t lower temps any, but upper 70’s isn’t to bad. I’m not super familiar with what options are available, or the performance you’d need to justify the purchase, but I’m sure there are at least a few that would increase your output. Something to remember here is that with an led tube the entire light source should be going toward your plants. While a flouro takes into account the output of the bulb that you have to try to reflect. So a 40 watt led tube and a 40 watt aren’t flouro aren’t created equal.

For the 8x4, hard to beat 2 600’s when you look at price for performance. What are the chances you could maybe upgrade the ventilation and stay with the 600’s? I have been messing around with a 6" hyper fan that’s pretty impressive. You would probably want an 8" or 10", but they are very efficient, move good air, and come with a model specific speed controller. Priced a little higher than budget fans, but a very good value in my opinion.

If you’ve got money burning a hole in your pocket, horticulture lighting group has some large footprint lights that people are claiming put off very little heat. But you’d have to research and check reviews yourself, I don’t have firsthand knowledge.

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wow I wonder why i am still not using led’s? footprint per LEC is little over 3x3 and like I said I have ballasts out of space and yes they are dimmible :wink: cost wise 1 bulb ballast and adapter is nearly 400 CDN that’s likely less than 4 mars hydro the LEC’s throw off high UV much like LED but light is real light meaning everything is real colour not purple red yellow or blue. I am running 2 lights 18hr’s of the day 1 the other 6hr’s in a 9x6 room with a 6" exhaust even with all three on at same time I can still keep temps 78-80 running current cycle my temps sit around 72-77
I am not using vented hoods or tubes just open shades even if in theory you ran 3 in your 4x8 your watts would drop by nearly 300 which is easy 5-6f temp drop if not more
I am constantly playing with ways to make my grows more efficient and for me it was a logical choice my next change is going to be adding my light mover with a short track 30" A funny thing I am killing pests in my mother space t5’s but none in any of my LEC spaces



I think I am going to go LEC route instead of LED route and try it out in my 4x4 … I found this that comes with the conversion kit, so all I need to figure out now is a bulb … if your saying I don’t need a vented or glassed hood… I have a reflector I can use

am I correct in thinking I can just get something like this

and use that bulb for whole grow?

If that is the case, then yay… not to familiar with these brands tho

Sensing your sarcasm here, I feel the need to clear a few things up. Personally, I wonder why your not growing with leds too haha. But you’re obviously happy with what you have, so there’s no reason for you to be presented with other options. Unlike the op, who said he was looking at different options.

I offered 2 extremely low cost options, and 1 that would be much more expensive. I don’t remember making any smartass remarks about your suggestion, was it necessary to do it about mine? I build my lights, and would like to help others do the same. I don’t want to steal info from guys on YouTube and profit from it, that’s for sure! I simply pointed out some options that I felt viable. I don’t have any experience with lec, so I just didn’t comment one way or the other. You may very well have a better suggestion, but I can’t personally confirm or deny that.

No light that I recommended has any visible red or blue, so 10 years ago. But plenty of people are still successful with them. They are/would be all white. In my experience, led’s don’t really put off that much uv. Even the ones that include “uv diodes”, I’m almost positive they just barely reach the uva spectrum. This from looking at spectral graphs, not taking some advertisers word for it. Uva doesn’t really do much for plants. It may slightly produce more resin, but it’s more likely that any difference in resin production was due to a different method of stressing before harvest. Hard to say when you starve on nutes, split the stem, and/or leave in dark/cold before harvest. Uvb may be another story, but I’ve yet to see any data supporting there are viable Uvb producing diodes available. In my defense, I haven’t really looked either. I’ve been way to busy keeping up with cramming the same amount of photons from half the power.

I didn’t realize that the op had a bug problem? But if your light keeps them away, then you do have a positive for it. I just don’t see the relevance, he is trying to run cooler temps.

One thing I noticed you didn’t mention that I’m fairly sure I’ve read you post about earlier, yeild. Have we come to terms yet with average growers using led easily surpassing the gram per watt mark? I see it every day on this very forum, and others. Yet 1 g/w is still a bragging point for hid growers.

I’m glad @AngelicSoul chose your light, and hope he does great with it! I’m here to enjoy people doing this, not ridicule them.


Green power by philips they come in 3100k and 4200k the 3100 can be used whole grow but the Vivosun version may be just as good?

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I have never had a issue with heat in my 4x4 tent so far…and I have a 6" extraction fan on that one… I really never go over 75-77 in it… even when I ran my one 600w hps in it… I never went over 77… I am still new to all this growing stuff… But I have a 4ft 8 tube T5 thingy in that with my 2 week old from seed babies… 8 of them… so I am going to run outta room …but since I am having a heat issue in other tent… my plan was to get something set up in my 4x4 now… before I run out of room since my other tent is about to come down… take one hps out of there… and down it to one and move four plants to that and leave four in my 4x4… then that gives me time to get stuff sorted before my next grow… I didn’t look into it at all far as building my own lights… … but I am not very erm… diy kinda girl… specially with anything electronics and what have you… that could end in disaster with my house burnt to the ground prolly lol

Oh and I dont have a bug problem… thank god… cuz I would totally freak but if they saying LEC keeps creepy crawlies away then I’m all over it

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Sounds like you found the option that works best for you. Happy growing!

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