Aquaponic Gardening

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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 Vlad Jovanovic on August 13, 2012 at 12:54pm

Wow at 113 it might be mission impossible for good fruit set and most of the time when it's anywhere even near 100 (let alone above) we get a lot of flower drop due to the heat. I have a bunch of different organic hydro, hydro, and pee-ponic systems I play with...So much of what I might suggest as far as P-K might not be advisable in a system with fish... other than

Right now I'm on this kick where I'm using magnesium (in the form of Epsom salt) to extract and reclaim phosphates from my urine, so I'm using a lot of that for phosphates at the moment. The cool thing is it's "organic", but yet the phosphates are bio-available immediately...

But, I'm guessing that if your system has been running a while your prob more than good on P and if you buffer with potassium bicarbonate at least some of the time that would be a good way to get some K in the system.

Peppers like toms are not photoperiodic either, but they seem to just flower when they reach a certain stage of development and the high/low temp difference doesn't seem to matter to them. So, I'm guessing you'll have more luck with them...Especially if they're hot peppers and not bells...

Peppers, toms, cukes, zucchini, potatoes...are some common day neutral plants that I can vouch for, none of them can be forced flowered by manipulating the light/dark.

Comment by Jon Parr on August 13, 2012 at 12:29pm
Interesting info, Vlad. I get tomatoes year around in the greenhouse, without any manipulation of temp or light, or nutes for that matter. However, I do live in an extremely mild clime. David, nice to see a fellow CMH fan.
Comment by David Schwinghamer on August 13, 2012 at 11:56am

Well those temps are close to impossible here in the summer, today its going to be 113 as a high. I guess I have to wait til November for those temps. What products do you use for the P and K in your aquaponic system. My toms are in a raft bed now. Is this plan the same for pepper plants?

Comment by Vlad Jovanovic on August 13, 2012 at 11:17am

David, since tomatoes are non-photoperiodic plants (day neutral) you can't use lighting to force flower them. They just don't respond. You can however force flower them by plying them with lots of phosphorous (P) and potassium (K) and keep daytime temps at around 75 degrees and night time temps at around 65 degrees. It is actually this high/low difference in temps that is the trigger mechanism that toms respond to (the high P-K helps give them what they need when switching gears into reproductive mode...but the temps are the initiator)...

You can run those lights 24/7 and they'll still flower and set fruit just fine as long as the temps are good and there's enough P-K. I've tried it. It's a waste of electricity, but it works fine. I really doubt there's any reason to keep the lights on more than 18 hours at that point, but you can and it wont make a difference (other than to your pocketbook). 

Comment by David Schwinghamer on August 13, 2012 at 10:41am

Does anyone here know anything about force flowering tomato plants and how its done using lighting? I have a 400 watt ceramic metal halide light with reflector connected to a timer. Its on at 5 am and off at 8 pm.

Comment by Vlad Jovanovic on May 15, 2012 at 4:22pm

I personally am partial to metal halide because 1) I like my babies to be short, stocky with tightest inter-nodal growth possible and nice thick stems, and I grow a lot of day neutral plants (peppers, tomatoes etc)...So I can flower just fine with MH bulbs. And 2) I live where it's cold for a good part of the year, so I can use the heat (MH bulbs are the least efficient of the HID bunch, so they give off the most heat energy)...

That being said though, I don't think you could go wrong with any of Jon's suggestions, particularly full spectrum ceramic metal halide (CMH). The only potential "drawback" being that you are in northeast OH and want a 12 month growing season (I used to live in Cleveland and wish you the best of luck, so there will be months where you could probably use the extra heat of the MH bulbs)...Not that CMH are cool running lights by any stretch I'm sure... HPS bulbs run slightly cooler than MH as well, as they are a bit more efficient. The only reason I haven't tried out the new CMH is that they are unavailable for purchase in my country.

Anyways, IMO pretty much anything in the HID family will do you right, as well as being more cost effective than any fluorescent lighting ever will.

For the last year or so I've personally been keen on Phillips Son-T-Agro plus bulbs. It's basically an HPS bulb with a 35%  'blue' (MH) element added for balanced vegatative/flowering...Sort of a "do it all" kind of light. I am very pleased with them thus far.

But whether MH, HPS, CMH, Son-T, Chrome dome HPS, I doubt that you or your students will be disappointed, and the degrees of difference between the above mentioned bulbs probably become matters of finesses or personal preference (or very situation specific).

Comment by Jon Parr on May 15, 2012 at 3:20pm
I get CMH bulbs here:

4) 400 watt bulbs for $166 shipped to my doorstep, 3x$52, 4th free, $10 shipping no matter how many you buy.
Comment by Jon Parr on May 15, 2012 at 3:13pm
You might try a HPS bulb called a chrome-dome, or a gavita. They have the reflector inside the bulb, so no need for an external hood to block sunlight. I have had luck with hanging vertical bare bulbs, but that style is better suited to tall bushy plants or vertical gardening than low/flat lettuce and rafts. My favorite bulb is a Phillips ceramic metal halide, full spectrum, excellent bulb life, and run much cooler than HPS or MH
Comment by TCLynx on May 15, 2012 at 12:25pm

Hetal halide is probably the way to go to get the most bright without blocking natural light.

I'll let people who actually use artificial lighting to direct you to the formula for how many/what wattage you need to cover specific spaces at what distances.

Comment by Ralph R. Zerbonia on May 15, 2012 at 6:24am

Hi, I am working with a school system that owns a greenhouse and wants to turn it to Aquaponics. The greenhouse has two sections each 22X54 ft. We are in Northern Ohio and want 12 month growing. What kind of supplementary light would you all suggest and how may we deploy them so they don't block the sunlight we do get? How many will we need. Please assume price is not an issue.


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