Led - watt per square foot?

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Ph 007

Ph 007

Anyone know what is the best watt per square foot
I have the lights below I can dim them I'm looking how far i can dim them to save electric but not affect yield

I have 2 of these in a 4×4
240w lm301h with cree xpe2 660nm 730nm LG UV switch QB led board

If got them dimmed down to 190watt per pannal at the moment and growth is good so thats 400 watt in a 4x4

High efficiency light QB Led grow Boards

· Full Spectrum for better results

· Reliable passive cooled design, 10mm thickness heatsink

· Better canopy light penetration with diffused light

· Perfect performance for veg and bloom

· Dimmable Power Supply included
 
Grownsince95

Grownsince95

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A common number I see suggested is 30w/sq ft. I am currently running 22w/sq ft but actually plan on doubling that so maybe 30 is a good place to start? Im on my first LED grow so still learning.
 
Ph 007

Ph 007

I read 30 - 35 last night but they where old forums 3-4 years so I though technology would of been better and maybe needed less watt see lol.

What room temps do you run yourself with these boads , im runnibg 84-85f in the day and night 75-76f
That's with no added c02

I was running much cooler but looked like shit and loads defficciantcys and drink really dam slow
 
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Grownsince95

Grownsince95

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I read 30 - 35 last night but they where old forums 3-4 years so I though technology would of been better and maybe needed less watt see lol.

What room temps do you run yourself with these boads , im runnibg 84-85f in the day and night 75-76f
That's with no added c02

I was running much cooler but looked like shit and loads defficciantcys and drink really dam slow
I try to stay within the VPD happy zone when I can. In the flower tent that's 77 to 80 with 60% rh with the lights on. Current grow im going to try to drop both as low as I can in the last 2 weeks hunting for more terps and color. I've never tried it because with my old HPS setup it was really hard to get my room down to even 75 degrees. My first impression of LED lights is that they've made some environmental issues easier to deal with. One day I will upgrade to some really fancy ones haha.
 
Ph 007

Ph 007

I try to stay within the VPD happy zone when I can. In the flower tent that's 77 to 80 with 60% rh with the lights on. Current grow im going to try to drop both as low as I can in the last 2 weeks hunting for more terps and color. I've never tried it because with my old HPS setup it was really hard to get my room down to even 75 degrees. My first impression of LED lights is that they've made some environmental issues easier to deal with. One day I will upgrade to some really fancy ones haha.
I could get my room down to 75 with ups and cook tubes, and never give muxh colours, I use to grow at 76-78max and that worked best for me 70-72 lihht off,,

These leds if tried 75-78the grew in but shit load of dificciancys thst I never had with ups, since upping day to 83-85 86 max usually bounced 83.7-85.8g and the seem to be doing very well so for the drink like my hps use to now, cooler temps drunk slow as shit,,,,
Also if looked to vpd but looked to much work adjusting diffent stages or growth,,,
With hight room temps now my humidity is 50-60% u like tbis less chance of mold in past his could be 58-70.

If seen great difference in yield bums fat from top to bottom.not just the top buds like hps :)

Just problem is now I don't get problems cooling room I get problems heating it lol, Im Using same amount of electric I use to with 600 watts hps now with heated blasting but they loving it.
If been doing on leaf temps lately and if figure out most my thermos metres are out of put 4 in same.room same spot all.diffrent reading lol..


Just one thing im still not 100% sure of now is what lights off temp should be, I don't let drop below 75f now because day is do hight..
But
Leaf temps are same now on led as they where on how, and HPS and hps night I'd have 70-72 night,, it's makes sense to me to be on 70-72 for led then as leaf temps is the same, well.i assume.its the same.i never checked hps leaf temps before see, only since had led I've done this


It's weird I'm.still.okayong about but flower room with 83-86 had worked best for me ..and leaf temp is hight 81-86f

But veg tent t5 cfl lights day 77-78 leaf temps are 78-81 it tried hihwr the don't like it,
If tried these leaf temp.with led but the don't grow lad well as leaf temps 81-86f
 
NorGrower

NorGrower

30w/sq ft definitely sounds reasonable but what's worth considering is that this varies based on the lamp's efficacy, i.e. how much light a lamp emits per consumed watt. In your case, your board with Samsung's 301h + Cree XP-E2 should produce an impressive system efficacy of around 2.3-2.6 µmol/J depending on driver and temperature. For a lamp with this efficacy, 30w/sq ft is good.

However, for anyone else with a lesser or greater lamp, the same 30w/sq ft value may not be applicable for you. If someone with, let's say, a generic Chinese "Amazon" light would calculate the needed watts for a grow space, it could very well be 60w/sq ft as the generic lamp is far less efficient, often around 1-1.2 µmol/J.
On the other hand, as quality diodes become even more efficient, the 30w/sq ft rule of thumb could go lower as diodes increase their efficacy. Imagine a lamp operating at an efficacy of 3.0 µmol/J, around 25% more efficiently than today's high performance lamps, it would be enough with 22.5w/sq ft to achieve the same quantity of light.

... sorry. I may have gone a bit off topic. Yes, 30w/sq ft for your grow is great :).
 
Ph 007

Ph 007

I been dimming my dimmers down 1 quarter from max,
Iv been dimming down from 240 to 200watt I use a measuring thing you put put the plug, reason for the dimming 1 they seem a little to bright and 2 Iv been needing to heat my room lights on to room temperature to 85f
To get leaf temprutute right

If also been testing ight temps at 75-76 but last 2 days in testing night at normal 72f min.
Do you know anything about led and temps, If tried lower temps the do not like it at all,
I think I got day temps right now just need to perfect night temps.

Room at 85f with my led gives me same leaf temprutute as a hps light, so really it makes sense to keep night at same as hps would be.
If read night with led should 76 if the day us 85 that

I might go back to go hps as.it acutely might be cheaper to run as with led I'm needing to blast heaters in the day,.

I might even do this
Insted of my.usually 600 watt hps
Have 1 x 400 watt and 2 leds , one either side of the 400 watt hps so I could run baxk in hps.temos at 75-78f
So total of all then 3 light is 600 watt

And you said you rumbled on lol
 
Aqua Man

Aqua Man

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30w per sq ft is for flowering you won't need to run that in veg.

More importantly is the intensity and coverage. About 600 ppfd max in veg for 18/6 and aboit 900ppfd in flower 12/12. You need to take into account the number of hours the lights are on when considering intensify.

Notice 900ppfd in flower (without co2) then 600 in veg. Then look at the hours... in flower you are running 1/3 less hours so you increase the light intensity by 1/3 to keep the DLI similar.

So if you have an android download light meter by my mobile tools dev and for veg 15k-45k lux and flower 45-65k lux. Always start at the low end and work up. Adjust height and intensity to get the most even coverage at the ideal intensity.

With 30w per sq ft you should have no trouble hitting those numbers.
 
Aqua Man

Aqua Man

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I try to stay within the VPD happy zone when I can. In the flower tent that's 77 to 80 with 60% rh with the lights on. Current grow im going to try to drop both as low as I can in the last 2 weeks hunting for more terps and color. I've never tried it because with my old HPS setup it was really hard to get my room down to even 75 degrees. My first impression of LED lights is that they've made some environmental issues easier to deal with. One day I will upgrade to some really fancy ones haha.
VPD to use properly should take leaf temps into account... the temp of the room is handy but the temp of the plant is what is key. There are many things that affect this like airflow, amount of IR lighting provides, transpiration rates.

This may interest you.

 
Ph 007

Ph 007

Thanks so early flower first 3 week is classed as veg ?

How do I mesure that ppfd , have looked into it last few days what mature would I need for led? 2 types iv heard of flux and something else forgot the name lol..

So that android mesures led ppfd Is it?

What about night temps?
^^
My day temps are 83-86 max
It hits 85 fan kicks in and room temps drop a to 83-83.5f then repeat
 
Ph 007

Ph 007

VPD to use properly should take leaf temps into account... the temp of the room is handy but the temp of the plant is what is key. There are many things that affect this like airflow, amount of IR lighting provides, transpiration rates.

This may interest you.

Iv also been looking at this mate room is at 83-85f and humidity is 58-60% today I put humidifier in flower room plant are 1 day I to flower and got humidity at 70-75% think the for cart says room temp 85 humidity 75-80% i think, i got my outlet fan feeling at just 10% 6" exhost fan,
I'm still leaf ing vpd I'm still trying to understands the air flow bit
 
Aqua Man

Aqua Man

Staff member
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Thanks so early flower first 3 week is classed as veg ?

How do I mesure that ppfd , have looked into it last few days what mature would I need for led? 2 types iv heard of flux and something else forgot the name lol..

So that android mesures led ppfd Is it?

What about night temps?
^^
My day temps are 83-86 max
It hits 85 fan kicks in and room temps drop a to 83-83.5f then repeat
The app measures in lux so it can only be used with full apectrum lights like you have.... for those reading that means NOT BLURPLES. From flip start at 45k then work up based on plant response.

You want leaf temps of 75-80 with 77 LEAF temps being ideal. Under my hlg in my room under my conditions with my airflow thats about 82-84f. If you see what I did there I suggest and IR temp gun to know for your room. They are cheap on amazon.

 
Aqua Man

Aqua Man

Staff member
Supporter
Iv also been looking at this mate room is at 83-85f and humidity is 58-60% today I put humidifier in flower room plant are 1 day I to flower and got humidity at 70-75% think the for cart says room temp 85 humidity 75-80% i think, i got my outlet fan feeling at just 10% 6" exhost fan,
I'm still leaf ing vpd I'm still trying to understands the air flow bit
I like an oscillating fan that just makes the leaves wiggle a little as it passes. So key airflow is under and through the canppy. Leaves transpire from the bottom so you want good airflow there. Contrary to seeing many ppl having the fans blowing down on the plants.
 
Ph 007

Ph 007

I had a laser heat gun few days back if tried lead temps 75-80f, now today if Been testing leadf emps 80-85

My veg temp t5 cfl lead temps are 77-79 the grow well but also todsy if upped to 80-85 room temps 83-85f
 
Ph 007

Ph 007

I like an oscillating fan that just makes the leaves wiggle a little as it passes. So key airflow is under and through the canppy. Leaves transpire from the bottom so you want good airflow there. Contrary to seeing many ppl having the fans blowing down on the plants.
I might extractor fan my fan down to 5% idel and I will move my oscillating lower down so it blows my plate from the side
 
Grownsince95

Grownsince95

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VPD to use properly should take leaf temps into account... the temp of the room is handy but the temp of the plant is what is key. There are many things that affect this like airflow, amount of IR lighting provides, transpiration rates.

This may interest you.

Very good point! Thank you for mentioning that..So how many degrees would you say a leaf temp could differ from room temp? I've been trying to work in a general range and not go nuts trying to hit specific numbers...for instance in veg 75 to 80 deg with 65 to 70 rh and flower 70 to 80 deg and 60% rh until the last 2 weeks. Trying to just stay in that blue shaded area of the chart. How much can actual leaf temps throw that off ? Genuinely asking not sarcasm...
 
Ph 007

Ph 007

What you recommend for night temps mate?

Tomorrow might drop temps down like you just said and het leaf temps at 75-80 also this will save me needing to blast lil radiators in the day
 
Ph 007

Ph 007

Screenshot_20200911-001120_ColorNote.jpg

Note ready for tomorrow test ;)

Aguat man I know I'm going on But what do you recommend for light off temps?
 
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