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Artificial Lighting


Artificial Lighting

Grow light discussions; HID, florescent, LED, and anything else that isn't the sun itself.

Members: 138
Latest Activity: Nov 13, 2017

Discussion Forum

How high?

Started by Ian Cameron. Last reply by Ian Cameron Dec 29, 2014. 5 Replies

Now that I've migrated from T5's to HID's, I'm wondering how far above the plants these beasts should be. I'm running a 1000w MH dialled back to 75% above my 5x5 raised bed, with lettuce, kale and…Continue

HID's, what are the pros and cons for MH and HPS?

Started by Ian Cameron. Last reply by Ian Cameron Dec 20, 2014. 7 Replies

Hi Folks, well after 2 yrs of T5's, I have switched to HID's for the balance of my winter season in the in-ground green house. I have done some research but cannot find any definitive reasons to go…Continue

HID lighting

Started by Chris Blanco. Last reply by Jeff S Dec 19, 2014. 9 Replies

I have a lighting question, I am getting ready to run electrical in my grow room. The grow area will consist of 2 8' x3' GBs put end to and and 2 8'x3' DWC sitting just below the GBs. The total foot…Continue

HID's raising cain with my timers

Started by Ian Cameron. Last reply by Ian Cameron Sep 27, 2014. 2 Replies

Seems I can get a timer to hang together for more than ten cycles when firing up my MH's. Should I be using a relay of some sort? Any ideas?Continue

Comment Wall


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Comment by LogicalHydro on June 2, 2013 at 6:25pm

I agree, the LEDs are very attractive lights. Did they specify why they were comparing HPS against LED? It doesn't make a lot of sense for lettuce, I would have went with MH or Fluoros. They should show kW usage for the 2 during the grow. That would make them look even better. That price does sting a little though.

Comment by TCLynx on August 14, 2012 at 6:38pm

Eric just made a thread for this Jacking over to the


Comment by TCLynx on August 14, 2012 at 6:30pm

I once asked the question about using potassium chloride instead of salt but I never really got an answer back from the people who know more about fish than I do.

It seems to make sense to me that the potassium chloride would work to provide the chloride mitigating nitrite poisoning when dealing with such cycling up issues, but as I am definitely not a chemist, please do more research and don't take my word for it.  However, I don't know that one would want to constantly be adding the chloride if using potassium chloride for the potassium supplementation.

Comment by Jon Parr on August 14, 2012 at 5:54pm

Mask on, gettaway van idling out back

The reason I inquire about KCl is that I have not, and probably never will have, the luxury of buffering up. I have never had my pH naturally go below 6.8 (and that was a miracle), and as I understand KCl will not affect pH, and yet still supply usable K and Chloride. However, I'm not the chemist I thought I was in high school, so feedback is appreciated

Comment by Vlad Jovanovic on August 14, 2012 at 11:39am

TC, just out of curiosity...why do you say "in a pinch"? Don't folks salt their systems with NaCl for the chloride ions (tonic for the fish, mitigating nitrite poisoning blabla...)? Potassium chloride seems like a grand way to add K for the plants and provide some chloride ions for the fish at the same time...Is there any reason you know of that this would not be so?

(Jon, cue the music and put your ski mask on :) ...

Comment by TCLynx on August 14, 2012 at 7:12am

Potassium Chloride can work to provide potassium in  a pinch but for me if the pH is fine, I'll usually use some seaweed extract to also get trace elements along with the potassium.

As to the tomatoes and flowering.  Toms where I live are a spring and fall crop since summer is too darn hot.  Now we usually don't get the super extreme heat but since I'm in a humid climate it doesn't usually cool off enough at night for good flower/fruit set during the extreme heat of summer.  If you can keep the plant alive and well through the extreme heat, then once the temps come down a bit and you can get the right differential between night and day you should hopefully start seeing some tomato production.

Comment by Eric Warwick on August 13, 2012 at 4:28pm

Jon, yes you could, but it's not as efficient as a K buffer. Ultimately, if your pH is good, then your nutrients are going to be absorbed better, which equals less deficiencies. I think, ultimately, if you're making your own nutrient solutions (hydroponic) then KCl would work. I guess it's cheaper to use Calcium Bicarbonate to buffer as well. Anyways, whatever works. 

Comment by Jay Wolf on August 13, 2012 at 3:37pm

Anyone have experience or know someone who has used water cooled HID's?

Comment by Jon Parr on August 13, 2012 at 2:13pm
Excellent. On the potassium issue, could one use potassium chloride? It certainly is cheap, just paid $12 for 50 lbs, and it's 51% K. Borderline threadjacking, here
Comment by Vlad Jovanovic on August 13, 2012 at 1:13pm

Yeah Jon, there's usually a natural difference in day/night temps that will take care of that...esp in a 'mild' climate. I don't think I'd ever bother manipulating temps or anything. (Well I do that in the winter when growing in the house, but that is a secondary effect...mostly I'm heating for me and the missus...the plants are just lucky that way).

Just trying to give David a heads up on how/why things happen...I guess if I really, really friggin wanted toms, or someone was willing to pay me a boatload of money to grow them and I lived in an extremely harsh (either hot, or cold) 'extreme' environment, that's how you'd have to do it...

The numbers I gave are 'middle of the road averages for optimum'. Obviously things will still happen outside of those temps. Thankfully nature is rarely that rigid. Those optimums averages I gave came from Papadopoulos (1991) and Benton (2005). Two guys I've really come to appreciate. 


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