Yeah, its not just the watts/sq ft. Its also the distance, over all temps, VPD, and the type of light. LEDS put out less infrared, so they can generally be run closer at any given wattage.
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Yeah I know how important VPD is @anon32470837 BUT running optimum VPD for optimal growth in such a small space is something im trying to avoid if anything bro. Thats one of the measures I’ve taken along with smaller pots and I’ve compacted the medium tightly into them to try and keep them manageable. The LEDs are in a fixed position at the top of the tent so the distance will only change as the plant grows. The meanwell has a dimmer built in that I can turn up or down instead of moving the lights if I need to 
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Sorry. I can get annoyingly pedantic sometimes. Bad habit.
My comment about VPD wasnt so much that it should be optimized, but that it can effect how the plants react to the light and the heat they put out - as far as drying out, respiration rate, etc.
No criticism intended, but Im curious - why you’re not trying for an optimum VPD? You are the first Ive heard say that.
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The tent is only 900 high bro. I’m trying to keep the growth and stretch to an absolute minimum. I have 9 reg seeds in 2 litre pots inside the tent so the plan is to purposely root bound them and keep them as small as possible. The plan is to remove the males as they show sex leaving just the females then reverse one of the females and open pollinate the entire tent. I’ve a scrog net on the ready to help control them if need be. It’s all purposely being done for a seed run only. I’m not expecting/wanting any smokable bud from the project.
Depending on how many females I get I will remove one or two, up pot into 11 litre fabric pots and move them into my main tent where they will be put back into a veg for a few extra weeks and flowered when my rdwc run is ready to be flipped.
I know you meant well with your post and I didn’t see it as pedantic my friend. I agree 100% with your statement about vpd so don’t stress 
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I totally missed that you were doing a seed run. Interesting project!
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Hello 
I’m working on a 2x2 ft box and trying to find out how to set myself up with lights like these. So far I know I want 3500k and 40w per sq ft. Could I get a hand? I’m in the UK (for shopping purposes) links or if someone could help me build it it would be an amazing help! I’m going from shop bought cfl’s which were plug and play for years to this and it’s making my brain melt trying haha. Anyway cheers in advance! B
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It looks a bit complicated but once I had built one with help from every one here, the next was done in just a couple of hours.
The hard bit will be finding a supplier in the UK as the supplier here is in Canada, they ship to the States so must do international shipping probably free for what you are looking for I will check when I get on my computer, unless someone knows before I do.
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Just spoke with digikey, they ship to the UK, if you spend 33 pounds or 50$ us you get free shipping. I can put a link up with the stuff you need shortly or someone else might beat me to it.
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We’re a helpful bunch here on OG ain’t we? 
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Ok here are the links for digikey. You are going to have to create an account and change it to the UK for pounds.
This is for a 150 watt driver which would give you 35 watts a sq ft.
https://www.digikey.ca/product-detail/en/mean-well-usa-inc/XLG-150-L-AB/1866-XLG-150-L-AB-ND/10222583
For the 40w a squ ft you would need a 160w driver not sure they do that, perhaps Mr Sparkle would be able to give a link for something just over the 150 watts that would be cheaper than the 240w which he said would need a minimum of 11 strips I think to run without running to much power through them.
This is for a dimmer if you want it.
https://www.digikey.ca/product-detail/en/tt-electronics-bi/P160KN2-0EC15B100K/987-1572-ND/3587330.
As you can see from the above discussion, these lights seem to be more powerful than first thought, and we are having to either turn the power down or raise the lights. I am running 30w a sq ft and it works very well for me. So running a 150w driver in a 2x2 would probably be sufficient. I think Trevor Lahey runs 10 strips on a 150w driver x 2 in a 4x2 ft tent with great results and thinks its overkill.
I have had to raise my lights to 12 inches in veg, and I am just seeing the plants start to recover now.
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I built one with the parts shady listed and infi from this thread. Honestly the hardest part is drilling your holes to mount the boards and not screwing up… I had to go from self tappers to machine screws/nuts cause of slightly off holes.
22"x22" 10 of the 3500 k 22" strips and the 150 meanwell AB driver plus potentiometer. I think I’m I to it for about 150 canadian
edit also added a sonoff pow to make it have it’s own timer
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Nice looking rig 
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Totally impossible to read this thread stoned.
Thank goodness for sil’s.
And floods.
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One thing to watch out for when wiring the strips in series is that the strips themselves have a max working voltage.
From table 2, note 3 of the datasheet for the eb series gen 2:
Since these have a vf of 20, then 3 should be the limit in series (as far as I understand it).
I found this out earlier this week when proposing my strip build over on the LEDGardener forum.
Can probably get away with it, but I’m looking at 100% parallel options for now. 
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I forgot to post it here, but I managed to re-use components from my old mars hydro 900w with those bridgelux strips. works really nicely
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Well here’s my understanding of it but don’t take it as gospel, your voltage is divided across all the items within the circuit based upon their current draw and resistance, now if the strips are say absurdly mismatched in a sense like one strip has three times the resistance of the other strip in say a 2 strip series circuit it will pull 3 times the voltage as V=IxR .
But we are limiting the current, so the strips will only pull the max amount of voltage based upon their resistance which is affected by temperature and their manufacture. So even with variances they won’t be that drastic.
That 60v is the operating voltage of the insulation, so say in a situation like your feeding a circuit that has one strip at a “fixed” voltage of say 80v but your also limiting the current to say 700ma the strip will take 19.5v of that leaving the other 60.5v to be taken by the insulation wire ect as the voltage is fixed and it has to go somewhere.
But say your hlg drivers they are constant current and constant voltage, but your circuit will only take what the limiting factor is whether current or voltage, your xlg drivers are just constant current, but the voltage will range within a spectrum with them such as example an xlg-240-l-ab has 178 ~ 342V range which would dictate you only being able to run 9 well “9.13” to 17 of the 19.5v strips, where as say if you hooked up only 6 strips to that same driver in series, then your gonna have a stray 61v that has to go somewhere which will be your wire, insulation, connection terminals and the likes and thats when your gonna run into that over voltage situation. But again that when feeding a fixed voltage or a voltage with a fixed lowest point and your drawing less than that.
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I think I see what you mean. Seems to make sense to me. It was news to me that the number was so low, I assumed it was at least 200v.
Right now I’m planning 10 EB2 strips in parallel on an XLG-100-24.
Since it puts out 4 amps (16-24v constant current region, strips are ~20v), with 10 strips, the strips would be at .4a.
I’m thinking if I run them that low I wouldn’t need a heat sink but I’m not sure…
They max at .7 amps and I’d be running them at .4.
Still just white boarding, but I could put that light together for about 120$ including shipping from digi key and the metal from home depot.
In theory, I would be using it in a 2x2 tent, about 25 watts per sq foot at 12 inches in flower.
Not sure yet, just brainstorming…
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well at the nominal .7a most people don’t run heatsink anyways look at toast and trev’s builds or the handful of other people running them, they would just be warm to the touch as they do run quite cool, i just mounted mine to an aluminum plate cause i could and just incase i needed it but honestly i could run them by themselves and they would be fine.
Also right now im running mine at around 23w/sqft at 18" and was getting photo toxicity issues when i was running in the 35-40w/sqft range so… yeah what that target should be is more up in the air and depends on the environment.
Also id look into the xlg-150’s as its only a couple dollars more, better to have too much that you can dial back than realizing you have too little and need to get a new driver, not saying that will happen if planning for 25w/sqft but just a consideration.
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I think you’re right, I probably will go for the XLG-150-24. It’s like 3 more dollars… Haha. Plus if necessary the 150 can dim all the way to about 80 watts from the wall, thanks for the advice!
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