How many lumens for 3x2?

[CreamCannon]

Looking at getting a T5 fixture, only have a 3x2x6ft space. Hoping to grow 2 plants. How many lumens do I need? will a t5 4 lamp light work?

 

[Guest]

Hey CC,

I think a 4 lamp t5 would work great in that space for 2 plants for vegging. Could probably top a couple of times and have plenty of light for veg. I have always flowered under a 400watt hps- 45,000 lumens, so I have no experience to offer for just T5 thru finish. You're gonna have to deal with heat though if you use an HPS. Very little heat with T5, but you just cant expect best results. Maybe LED would be an answer?

Just a few thoughts

Keif

 

[CreamCannon]

Hey CC,

I think a 4 lamp t5 would work great in that space for 2 plants for vegging. Could probably top a couple of times and have plenty of light for veg. I have always flowered under a 400watt hps- 45,000 lumens, so I have no experience to offer for just T5 thru finish. You're gonna have to deal with heat though if you use an HPS. Very little heat with T5, but you just cant expect best results. Maybe LED would be an answer?
Keif

I originally wanted an LED but they are pretty pricey, and the ones that I did find no one could give me a definate answer if theyd work or not... I was looking at these 2...

http://www.topledgrowlight.com/led-grow-light-200x3w.html#.VD8VnpRdWMA

http://www.topledgrowlight.com/mars-ii-led-grow-light-400w.html#.VD8VtJRdWMA

will either of these work for 3x2 space // 2 plants?

 

[BigBozat]

Meh

Meh

I originally wanted an LED but they are pretty pricey, and the ones that I did find no one could give me a definate answer if theyd work or not... I was looking at these 2...

http://www.topledgrowlight.com/led-grow-light-200x3w.html#.VD8VnpRdWMA

http://www.topledgrowlight.com/mars-ii-led-grow-light-400w.html#.VD8VtJRdWMA

will either of these work for 3x2 space // 2 plants?

I have/use the exact LED per your 2nd link (the Mars II 80x5w)... of the two, it's the better choice (becuz it has extra white spectrum lacking in the 1st)... that said...

Overall: *meh* ...
Reasonably suitable enough for veg, but hasn't been all that for flowering... had to supplement (in my case, using CFLs, but prolly should get HPS)... suspect the discrete spectrum bands are too narrow and/or don't include ranges that are beneficial (but underappreciated... e.g., green @ say, 510~540nm; see Black Dog LED) and/or simply aren't simultaneously intense enough to penetrate canopy sufficiently or diffused enough to provide coverage (without causing occasional spotting on leaves (I don't have a mover/track, nor could fit one into my cabinet)...

There's a reason it seems so relatively inexpensive on a $/w basis compared to the more expensive LED brands out there... cheaply made Chinese stuff (Mars II clones are all over Alibaba)... mine's OK, but have heard from others that some of the parts & joins can be poor quality... YMMV

 

[BigBozat]

Oh, forgot to address your specific Q in re: lumens... can't find my notes from when I bought mine, but short answer: the 400w model puts out plenty enough for a 3x2 area... just keep 'em low/close to the canopy (mine is about 4" ~ 6" above scrog canopy)

 

[CreamCannon]

Do you think a t5 would be just as efficient? maybe something like this..

http://www.amazon.com/gp/product/B00NMX5EGC/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=AGHGL81LFL69F

I know HPS would be great for the overall yield but im basically trying to conserve on electricity consumption. Also, an HPS system seems a bit more complicated no?

 

[BigBozat]

Do you think a t5 would be just as efficient? maybe something like this..

http://www.amazon.com/gp/product/B00NMX5EGC/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=AGHGL81LFL69F

I know HPS would be great for the overall yield but im basically trying to conserve on electricity consumption. Also, an HPS system seems a bit more complicated no?

Long story made short:
Either (Mars II 400w LED or Duro-Lux HO T5s) will 'work'... just not ideally as you may hope. Pick one, whatever best fits your immediate budget and/or what you're most comfortable with... it'll 'work' fine enough. Hell, I've seen satisfactory grows done w/ mixed 23w CFLs, so either the LED or T5 should 'work' well enough for you for the time being...

You can always improve upon later if you don't like the results (and, if you're ultimately going for both quality & quantity, you will prolly eventually move up and/or add supplemental lighting)...


Short story made long:

Define "efficient"?

If your definition of efficient is simply the most lumens (regardless of PAR, bulb/diode life, acquisition cost, how close you can place above canopy top, heat generated or anything else) per Watt input (aka 'luminous efficacy"), then the t5 linked above ostensibly = 20,000 lm @ 190w input = approx. 105 lm/w

IIRC, the Mars II 400w is something like 10,800 lm @ 170w draw {their specs show higher 198 +/- 5% (@ 120v), but their p/s is fairly efficient & when I measure it's really only drawing 170w}, so luminous efficacy is only = 63.5 lm/w...

So, on the face of it, the t5s would seem far more 'efficient'...

But, that's misleading...

The t5's are emitting all sorts of light at spectrums the plants can't use (PAR) and/or at peaks that don't necessarily align with what the plant most uses for photosynthesis, so a lot of energy gets effectively wasted... whereas the LED targets specific wavelengths (430~440nm, 450~475nm = blues; 620~630nm, 650~670nm = reds; 730nm far red/IR; and even a 'full' spectrum white) at which plants are most photosynthetically active), thus more 'efficient'...

To figure out how to adjust for all of this to come up with an apples-to-apples comparison to make a more precise 'efficiency' judgment is beyond what limited info is available (not to mention my limited knowledge of LEDs & T5s & relevant light/photosynth theory)... In the absence of better info, my best guess is it's prolly a coin flip...

Other thoughts:
The t5s prolly produce a better spread/coverage (if for no other reason than the larger footprint)... but you're in a 2x3 closet (w/only 2 plants?), so how much 'spread' is a concern seems dubious to me...

As 2-footers, the t5s will run a bit hotter than 4-footers... and generate more heat than LEDs, in any event... so you prolly won't be able to drop them as close to the canopy as LED... which translates to LED being able to get more energy onto the plants than the t5s (inverse square law and all that)... also, depending on airflow/ventilation, the T5s might get a tad warm (esp. if closet door shut & running lights 24/7 during veg), requiring you to invest more in ventilation (and power for vent fan)...

If you go T5s, get both the 6500K & 3000K bulbs, so you can mix n' match for diff growth stages...

The internal fans on the Mars II can be less than 'stealthy'... they're not a problem for me/my cabinet (don't have to worry about stealth so much), but others have complained (particularly on older models... the mfr purports to have improved w/ better, quieter fans on newer model)

The LED might also require you to do some periodic moving/rotating the plants to prevent potential spotting (assuming no room for a track/mover)

If it were me?
Faced w/ the same decision, I went w/ the Mars II... and don't regret it... but results were less than desired, and ended up supplementing w/ various CFLs... if I had room in the cabinet, I would mount T5s horizontally as supplementary lighting...

If energy consumption is the big issue, consider running the veg cycle on a gas lantern routine (do a thread search, if needed)... the extra hours of lights out should save u way more on your elec bill than trying to choose between the most 'efficient' LED vs. t5...

Finally, yeah, HPS might be a tad more complicated, w/ ballasts & heat, and whatnot. But there's a reason its favored for flowering...