Building a light @dbrn32


@Donaldj @dbrn32, I’ve been checking out these 315w CMH lights and i was curious to find out if a single one would function well in a 32×32 space? Id probably be doing 1 possibly 2 plants at a time.


Yessir if you can keep temps reasonable. If anything the space is a smidge small for the light, reason I mention temps. 3x3 is pretty ideal for a 315.


What sort of ventilation system should I look into for this light to regulate the temp? Any suggestions on brands and/or size?


They don’t produce tons of heat but are warm so almost any fan pulling out hot air would work even a small 4" duct booster fan


I don’t know that you need any specific brand fan or anything. Just keep reasonable air exchange and the ambient temp of your intake air within an acceptable range.


Thanks for the advice guys!


There are some fixtures with a cool tube. The bulb sits inside a clear plastic or glass tube and the exhaust fan pulls air through the tube. Those work great for removing heat. You can have an air circulation fan that doesn’t mix in heat from the bulb that way. Not necessary but very nice.


What k bulb works best in a 315w CMH light? They are offering a couple different ones on the bay, 3100k & 4200k I think. which one is good for veg and which one for flowering?


You can probably get plenty good enough results from seed to harvest with the 3100k.


If you wanted to have a veg-only room, get the 4200. Use the 3100 in your flower room, or optionally use 3100 for the whole grow if you only have one room.


Hey @dbrn32 how you doing? are you familiar with the Electric Sky product? They’re pretty pricey ,I was wondering if I could build something similar for cheaper or should I just outright buy it? I know you’re the Light King here , if you can make a list of things I need to build it to produce quality buds.I would greatly appreciate it. have 2 3’x3’x7’ grow tents . Thanks :v:


Yessir. Are you looking at the 180 watt or 300 watt model? Either can replicated with mid power diodes, something like quantum boards, bridgelux eb, or Samsung strips. All of them would provide higher efficacy than the electric sky lights too. I’m working on a light right now that’s about 220 watts probably 2.2-2.3 umol/joule for around $250 or less.


I’m looking at the 180 ,they’re calling for 2 for my size tent


Damn $250?that’s crazy lol Dude u gotta tell me what exactly I need for my size tent plz… I’ll start ordering tonight I’m pretty good putting thing together


I just left house to head to dinner with the family, can help you more later.


Ok thanks man enjoy your dinner u guys b safe


RapidLED has a pretty nice 3x3 COB kit for $509. I would get a 5000 K 70 CRI kit for the veg tent and a 3000 K 90 CRI for the flower tent. These are all pre-drilled, snap-together kits. Very easy. But you could probably build something similar with bits from here and there for a bit less.

I would cobble together the same design for about $350, but that’s because I build my own drivers and frames. There are advantages to being into electronics and metal fabrication.


Are the drivers just basically transformers?


They do that, but also provide protections.


No, you have a transformer and a rectifier (that’s the very basic description) to drop the voltage and then convert it from ac to dc.

A transformer, basically, steps the voltage up, down, or is used for switching in the case of an isolating transformer in a “shaving socket” where the mains voltage cannot reach the contacts until the circuit is completed by connecting the shaver or whatever and switching it on. The output is still ac though.