Opinions on COB Optic Choice for a 3x3

So Im getting the last few details together on my 3x3 setup and was wondering peoples opinion on whether they'd leave the COBs bare, use the LEDIL reflector, or use the LEDIL reflector ? I know a lot of people lean towards the reflector, which works perfect for 6 COBs in a 3x3, however Im running 9 COBs (3 sets of 3 50v Vero29 SEs, each set being driven by a HLG-185H-C1050B putting out 52.5w a COB) in my 3x3 reflective grow tent, so 1 COB per sq ft, and was wondering if this setup would benefit from me leaving the COBS bare or using the LEDIL Silicone Lens instead of getting the LEDIL Reflectors ?

It's really got alot to do with your hang height, if you can hang them high go with the silicon lenses as they will also protect the cobs to make them last longer. Make sure you have airflow around the heatsink also as this will dramatically increase the life of your leds

DrGreenT420 said:

So Im getting the last few details together and was wondering people opinion on whether theyd leave the COBs bare, use the LEDIL reflector, or use the LEDIL reflector ? I know a lot of people lean towards the reflector, which works perfect for 6 COBs in a 3x3, however Im running 9 COBs (3 sets of 3 50v Vero29 SEs, each set being driven by a HLG-185H-C1050B putting out 52.5w a COB) in my 3x3 reflective grow tent, so 1 COB per sq ft, and was wondering if this setup would benefit from me leaving the COBS bare or using the LEDIL Silicone Lens instead of getting the LEDIL Reflectors ?

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In a reflective tent, I would go bare no question.......to clean the cobs/fixture between rounds use 91% iso and canned air.

Thats loads of light. Id probably skip on the optics as long as your cobs are nicely spread out. Run it closer. Lenses will increase chip temprature and only help if you cannot hang your fixture low for some reason. For open space they do fine for edges but in a tent woth all that light you dont need either. Unles its for protection

TEKNIK said:

It's really got alot to do with your hang height, if you can hang them high go with the silicon lenses as they will also protect the cobs to make them last longer. Make sure you have airflow around the heatsink also as this will dramatically increase the life of your leds

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I have 6 feet of height in the tent so I should be able to hang my lights at whatever height. Thats one of the main reasons I was leaning towards the lens, was for COB protection. Is that the only major benefit of a lens over a reflector ? I see theres also the LEDIL reflectors that come with the polycarnonate lens. Im willing to do whatever would give me the best results with 9 COBs in the 3x3.

PSUAGRO. said:

In a reflective tent, I would go bare no question.......to clean the cobs/fixture between rounds use 91% iso and canned air.

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Oh wow. I never even considered just cleaning the COB with iso. Thats a game changer, I think you just sold me on bare.

Although it will increase the temperature I believe that having them protected will increase the overall life, you will loose about 8% with a lens, you will increase the temperature by about 20° too. But it will stop contamination and reduce dust build up. I have thought about this a bit and replacing the cobs every 2 years is a good option if you do not cover them as they are so cheap. I personally like the square lens from ledil as it will give an even spread as opposed to a hot spot.

TEKNIK said:

Although it will increase the temperature I believe that having them protected will increase the overall life, you will loose about 8% with a lens, you will increase the temperature by about 20° too. But it will stop contamination and reduce dust build up. I have thought about this a bit and replacing the cobs every 2 years is a good option if you do not cover them as they are so cheap. I personally like the square lens from ledil as it will give an even spread as opposed to a hot spot.

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Would there still be a hot spot with bare COBs ? Im wanting whatever would give me the most useable and evenly spread light, regardless of COB lifespan (although I prefer the look of the setup better with lenses). I figure if I can get 2 - 3 years out of these COBs I'll have gotten my moneys worth out of em and could just pick up some more. Might even look into getting a quantum board by then.

A bare cob does create a hot spot. The beam is round and usually 110-120 degrees. I think the square lens from ledil is 160 degrees, it's an asymmetric lens so it creates a square rather than a round beam, it will make the beam flatter than a bare cob, you should also be able to drop it closer to the plants to make up for the loss by using the lens.

You'll get more output bare, I've run cobs every single way in a reflective space(orca) and bare has the most pros vs cons imo......just lst, supercrop towards the perimeter and the lateral light loss will hit plant matter instead of walls==win ; )

PSUAGRO. said:

You'll get more output bare, I've run cobs every single way in a reflective space(orca) and bare has the most pros vs cons imo......just lst, supercrop towards the perimeter and the lateral light loss will hit plant matter instead of walls==win ; )

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PSUAGRO is a pretty experienced grower, choice is yours, some people believe that the hot spot is good too. I don't think it will matter too much as you are running enough cobs to get a pretty good spread anyway.

TEKNIK said:

PSUAGRO is a pretty experienced grower, choice is yours, some people believe that the hot spot is good too. I don't think it will matter too much as you are running enough cobs to get a pretty good spread anyway.

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Thats kinda what I was thinking, and was my main reasoning for wanting to go with 9 in the 3x3 instead of the tried and true 6 COBs in the 3x3. Thank you everyone for your input, it has helped me greatly. I guess I have 1 last question since I trust your guys opinions, I had my mind pretty set on having 1 3x3 specced for flowering with all 3000k 90 CRI COBs, and 1 3x3 specces for veg with either all 4000k 90 CRI, or 3500K 80 CRI, perhaps even a mix of both. Does that sound like my best option or should I just run 2 3x3s with all 3500k 90 CRI ?

I do not have an opinion on what is best there. Different strains like different colours. One thing that won't be an issue too much is stretch as you have the hight.

With COBs, Do Not Use Reflectors. Ever. Period.

https://www.rollitup.org/t/vero-reflector-usage-please-read.986327/

With 50 watts they are ok usually, that one seemed to have a problem, if you are going to use lenses over 50W then glass is best from my experience

hybridway2 said:

Didnt Dan from Timber just put up a thread stating reflectors wont be coming w/ the fixtures do to cob wear or something like that?
Geeze, i wonder what glass lenses do then?

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Wow...

Airwalker16 said:

With COBs, Do Not Use Reflectors. Ever. Period.

https://www.rollitup.org/t/vero-reflector-usage-please-read.986327/

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The issue was with a particular reflector not all things are the same. I still have products out there that are 8 years old with cobs running at 150W without an issue with a glass lens.

TEKNIK said:

The issue was with a particular reflector not all things are the same. I still have products out there that are 8 years old with cobs running at 150W without an issue with a glass lens.

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The issue is in tent grows. You shouldn't use reflectors of ANY kind with COBs when in a reflective tent.

After considering everyones suggestions and spending a few more hours browsing others posts and weighing my options, I think Im going to run them bare, and have them as close as a I can get to my plants without bleaching (6 to 14in ?). I may at somepoint down the road get some 120d lenses for shits to compare for myself but personsally its not looking like the cost of lenses for 9 COBs would benefit me a whole lot in a tent. Probably going to go with my flower room being all 3000k 90 CRI (possibly supplementing with red leds, any suggestions on this?). And 3500K 80 CRI for my veg room. Have there been any further tests done on how much UVB light increases potency ? I have done grows before, some ok, some half-assed, this time I plan on really going all out, as well as my first indoor under actually good lights, any tips for a first time legit indoor grow ? Thanks in advance, you guys have already helped significantly.

Randomblame seems to know what he is talking about regarding UVB, maybe try and follow up some of his discussions.