Dimming

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Wabbles

Member
What's with dimming ? When I read about most LED builds lights, I see people talking of dimming them. Why ? With other methods of
lighting ( HPS, MH, CMH,ect) I never see dimming suggested, only more power/watts .
What am I looking for in regards to LED's? draw at the wall ? Lumens at canopy ? Other ?
How am I to know what the sweet spot is ? What do I need to dial in LED's ?
 
Satax

Satax

Member
Plop,

Most of the people take it with dimming but they leave full power all the time.

Depending if you want to move your light during the grow or if you want to use the dimmer.

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Sorry for my English, hope you understand what i mean.

satax
 
Moflow

Moflow

Well-Known Member
Dimming to save on electric bill.
Versatility. Freshly rooted clones and young vegging plants need far less light so dim led fixture down and hang closer.
Although there are HPS Ballasts that have dimming capabilities. I used to have Lumatek digital Ballasts with the ability to run at 250 400 600 and 660
 
W

Wabbles

Member
Moflow said:
Dimming to save on electric bill.
Versatility. Freshly rooted clones and young vegging plants need far less light so dim led fixture down and hang closer.
Although there are HPS Ballasts that have dimming capabilities. I used to have Lumatek digital Ballasts with the ability to run at 250 400 600 and 660
Click to expand...
I understand dimming will save on elec. Veg , clones, & seedlings are under fluorescent t5/t8 fixtures.
Im talking Flower & what is best for results. If running at 100% produces better results, why dim to 75 % or 50 % ?
Is it only for elec bill savings ?
 
Boatguy

Boatguy

Well-Known Member
Usually higher powered fixtures are larger. If you buy an oversized light for your space, and dim it back you still have the large footprint, but can run it closer to your plants.
I have 2 hlg 648's in my little 2x2.5 at 75w a piece. With one at 150 i had to keep it much farther away and it didnt cover my area well enough
 
W

Wabbles

Member
Boatguy said:
Usually higher powered fixtures are larger. If you buy an oversized light for your space, and dim it back you still have the large footprint, but can run it closer to your plants.
I have 2 hlg 648's in my little 2x2.5 at 75w a piece. With one at 150 i had to keep it much farther away and it didnt cover my area well enough
Click to expand...
So if I have a 100w fixture that is "too much" for your canopy, why not buy a lower watt fixture in the first place ?
 
Boatguy

Boatguy

Well-Known Member
Wabbles said:
So if I have a 100w fixture that is "too much" for your canopy, why not buy a lower watt fixture in the first place ?
Click to expand...
In my case i couldnt find a single light that covered my canopy. So i run 2 dimmed, and gain growing height by being able to keep it closer.
 
W

Wabbles

Member
Boatguy said:
Usually higher powered fixtures are larger. If you buy an oversized light for your space, and dim it back you still have the large footprint, but can run it closer to your plants.
I have 2 hlg 648's in my little 2x2.5 at 75w a piece. With one at 150 i had to keep it much farther away and it didnt cover my area well enough
Click to expand...
Mak'er Grow said:
Dimming can also help reduce heat.
Click to expand...
so how do I know how far to dimm, so my plants get the most out of the light I'm using ?
What do I do to make sure the light runs efficiently & the plants don't suffer ?
 
Boatguy

Boatguy

Well-Known Member
Wabbles said:
so how do I know how far to dimm, so my plants get the most out of the light I'm using ?
What do I do to make sure the light runs efficiently & the plants don't suffer ?
Click to expand...
I keep mine at 35w per square foot for the entire grow. I do start with it run lower than that till the plants are established.
I have the light plugged into a cheap watt meter so i know what i am running the light at.
 
W

Wabbles

Member
Boatguy said:
I keep mine at 35w per square foot for the entire grow. I do start with it run lower than that till the plants are established.
I have the light plugged into a cheap watt meter so i know what i am running the light at.
Click to expand...
So, 35w psf is a consensus for the sweet spot ?
Is a digital power monitor meter what I need to dial in the light ?
thanks for the help
 
NukaKola

NukaKola

Well-Known Member
People do dimm HID’s. I flower under 600w and I veg under 400w. The problem with dimming HID’s is the bulbs are made to run at a specific temperature to produce a certain spectrum. So although you could technically dimm a 600w bulb to 400w you are better off just dimming the ballast and swapping to a 400w bulb. Since my bulbs are expensive, it makes dimming a bit more of a pain having to buy the proper wattage bulbs and switch them out whenever I want to dimm my ballasts.

LED’s don’t have that problem so you can take advantage of the electricity savings and run less wattage during different stages of the plants life by easily turning a knob.
 
W

Wabbles

Member
NukaKola said:
LED’s don’t have that problem so you can take advantage of the electricity savings and run less wattage during different stages of the plants life by easily turning a knob.
Click to expand...
this is what I don't understand, I buy a 600w HPS because I want 600w.

Why buy/build a 1000w LED then dim it to 500w ?
Why not save upfront $$ and just buy a 500w ?
Am i missing something ?
 
NukaKola

NukaKola

Well-Known Member
Wabbles said:
this is what I don't understand, I buy a 600w HPS because I want 600w.

Why buy/build a 1000w LED then dim it to 500w ?
Why not save upfront $$ and just buy a 500w ?
Am i missing something ?
Click to expand...
Because a seedling, vegging plant and flowering plant all have different lighting requirements. No point in wasting wattage if you don’t need it.

Say you have a 480w LED over a 4x4 which is 30w sq ft, great for flowering, but excessive for vegging. When the plants are seedlings or small clones you can run 100-150w, a few weeks later bump it up to 240w and then when it’s time to flower go up to 480w.

Vegging at 240w with the light at 16-18” above canopy will yield similar results as running it at 480w 30” above canopy for half the power consumption.

You can also get better coverage. Having 2 480w LEDs dimmed @ 50% will cover a much larger footprint than a single 480w LED running @ 100%.

It’s the same reason high horsepower V8 cars will cut back to 4 cylinders to save fuel when you don’t need it.
 
W

Wabbles

Member
cobshopgrow said:
underdriving leds gives you only benefits, so some people are willing to spend a bit for it.
underdrving HPS comes with some drawbacks in comparsion and the footprint of the light stays the same, no better spread.

it probably doesnt make sense taking a much too big led driver, but taking more leds is always good.
Click to expand...
so in a 4x4, what do i want to run at the wall ?

(nevermind HPS, I was just using as an example)
 
W

Wabbles

Member
Boatguy said:
I keep mine at 35w per square foot for the entire grow. I do start with it run lower than that till the plants are established.
I have the light plugged into a cheap watt meter so i know what i am running the light at.
Click to expand...
so im shooting for aprox 560w for a 4x4 ?
 
TintEastwood

TintEastwood

Well-Known Member
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