gwheels
Well-Known Member
WTF was the last bud? That is a beauty.
What would you recommend to replace a 1000w HPS in a 4x4 tent?
- Thread starter Dr.Pepper99
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Prawn Connery
Well-Known Member
Sensi Star. One of the all-time great strains, IMO.
JSheeze
Well-Known Member
Yea I saw that, I figured people were going to find that as contradicting (kinda hoping folks would read that far and venture to learn).
I think they're refering to using sunlight which they stated earlier as 55% non useable. Which makes it closer to 30% (4.3 ÷ .45 = 9.55%) but still wildly off.
Also after trying to figure out how they came up with their percentages in the section below that they tried to state in 2 different ways, doesn't make sense either, can't figure how they are getting their numbers.
I do know the chemistry behind the conversion is sound. The number of photons needed to convert is sound. The energy stored by certain wavelengths and chemical compounds is sound, so I think because the site is a conglomeration of people's info that some of it is off... ???
I base this assumption off my confidence of understanding of physics and chemistry not biology. So it's an educated assumption on my part take it with a grain of salt. But it makes me think I'm pretty close to the truth when Britannica also echoes what im saying/think (based on my physical science background again not my elementary understanding of biology)...
https://www.britannica.com/science/photosynthesis/Energy-efficiency-of-photosynthesis
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wietefras
Well-Known Member
Well that's what I said, there are several ways of estimating efficiency from light to biomass. Either way it's always a very small percentage, because that matches with the increase in biomass compared to amount of light given to the plants. Even if you don't know exactly how it works, its still possible to easily check the estimate since you can simply weigh the plants.
Also, again, just the photosynthesis step is only one step in the whole process.
Also, again, just the photosynthesis step is only one step in the whole process.
Yodaweed
Well-Known Member
You are using wikipedia to get your grow know? Come on man, go read the thread i linked you are totally confused and you didn't even read your own source, that's about a specific wavelength of light not overall absorption which is pretty much a wipe, nearly 100% of all lighting turns to heat. I'm not going to continue this useless debate, good luck.
JSheeze
Well-Known Member
Plants use 400-740nm wavelength, 570 is the average of those wavelengths and the maximum effeciency of photosynthesis at that wavelength is only 26% compared to the 34% quoted earlier. LEDs can emit essentially one wavelength so it's not a wipe.
The 34% referenced earlier is for the longest PAR wavelength closer to 700 which delivers the same amount of photons needed for photosynthesis but the energy of the photos is lower and so photosynthesis is more efficient because it uses less energy but same amount of photons. There is less energy left over after the reaction has utilized the 9 photons.
6H2O + 6CO2 + energy → C6H12O6 + 6O2
These are maximum efficiencies at those wavelengths given all other factors are optimal. Optimal to the point that light is the limiting reactant. Meaning CO2 is optimized, heat is optimized, RH is optimized, entire grow is optimized. Most people do this, create optimal grow conditions.
This is all from Britannica not Wikipedia, but grow knowledge is a conglomeration of all sciences so to assume its not translatable into growing mj is incorrect. Lot of electrical in lighting lot of thermal in heat mgmt, lot of physics picking spectrum. Understanding the laws of science can lead you to try different ideas that might actually improve techniques. Growing has evolved because of our scientific understanding of what the plant needs and how to supply that..
https://www.britannica.com/science/photosynthesis/Energy-efficiency-of-photosynthesis
"
The part of the solar spectrum used by plants has an estimated mean wavelength of 570 nm; therefore, the energy of light used during photosynthesis is approximately 28,600/570, or 50 kcal per einstein.
In order to compute the amount of light energy involved in photosynthesis, one other value is needed: the number of einsteins absorbed per mole of oxygenevolved. This is called the quantumrequirement. The minimum quantum requirement for photosynthesis under optimal conditions is about nine. Thus, the energy used is 9 × 50, or 450 kcal per mole of oxygen evolved. Therefore, the estimated maximum energy efficiency of photosynthesis is the energy stored per mole of oxygen evolved, 117 kcal, divided by 450—that is, 117/450, or 26 percent.
"
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JSheeze
Well-Known Member
Photosynthesis is the process by which biomass is made. The energy used to undergo photosynthesis is stored chemically to produce biomass.
Photosythetic effeciency is described by how much of the supplied light is being used to undergo photosynthesis. NOT by the different processes a plant utilizes to grow.
The plant gets all the energy needed to grow by converting the light energy into chemical energy, so what happens after its been coverted has ZERO effect on how efficiently it was able to transform and store the intial light energy into chemical energy (that it will eventually need and use to grow).
Your a applehead lol
I will concede that under high intensity light the average effeciency is like what you have said, in the 2-5%. If I'm wrong ill admit it. Upon further investigation it's only in the low intensity light that we can see the higher efficiencies (wavelength dependent), when light is the the limiting reactant.
Yodaweed
Well-Known Member
so, as we had said, nearly all usable light turns to heat, so 1000w of led is = to 1000w of hid = 1000w of incandescent. type of lighting does not matter only how much energy is put into the system.
WeedSexWeightsShakes
Well-Known Member
So if you have 3 sealed rooms one with 1000 watts of hps, one led and one incandescents. Would they all heat the room at the same rate to a stabilizing temp? Or would it be over time they would stabilize at different times?
JSheeze
Well-Known Member
Lol
You're not understanding that the tent isn't a closed system and the rate that light transfers into thermal radiation via mylar (97% reflective, that conducts its heat to the outer canvas which convects its heat to the room over a huge surface area- surface area of tent walls) ect is completely negligible inside your tent when dealing with heat issues.
In a closed system all energy will not degrade into thermal at the same rate.
3 types of heat transfer.
(Order of effeciency)
1. Conduction
2. Convection
3. Radiation
LEDs transfer most heat through conduction via a heatsink. This leaves a much smaller thermal gradient to come in contact with the air. This is why LEDs can be cooler to the touch compared to scolding hot HPS.
HPS transfer heat through convection. Very inefficiently. This is why an HPS is hot to the touch because the air does a poor job transferring heat away from the bulb.
Simply because the HPS operates hotter than the LED the resulting convection between both types inside the tent will have a different effect and a different rate of temp change.
Tents ARE NOT closed systems. The heat in your tents that you are dealing with is convection from the temps of the power supply tech and lightbulb NOT the PAR emitted light being reflected off the tent.
I've confirmed this with engineers holding masters degrees along with their engineering degrees. This is fact.
You use theoretical conditions to defend your "light is heat" argument but then use real world conditions to defend your photosynthesis argument. You can't pick and choose. I've said that under high intensity light (real world conditions) that photosynthesis is pretty much a 3% effeciency even though in a lab ect that it can be up as high as 34%. Either we are talking theoretical conditions or real world conditions. If it's real world then your wrong. And even in a lab or theoretically speaking, heat transfer from PAR light is the slowest form of energy transfer.
Use 100w to charge a battery in box vs use 100w to operate a heater in a box. The battery will slowly dissipate its energy eventually but the rate that both boxes exhibit thermal is completely different.
Rates matter...
JSheeze
Well-Known Member
If the rooms themselves don't conduct heat, they will all increase in air temp but each will increase at its own rate and all 3 will continue to increase in air temp forever (as long as power is supplied). If there's different quantities of matter in the room then that will also effect air temperature rates. If the walls conduct heat then their will be a "resting" air temp but they will achieve their "resting" air temps at different rates and at different temps.
Most walls are built with some sort of attempt at insulating against the outside temp but its not even close to 100%. When it's cold outside we run our heaters because the heat inside our houses is being conducted to the outside via our windows and walls, we have to replace that heat. In my experience the heat conducting properties of walls and windows in my house effeciently transfers the heat at the rate the LEDs produce convective heat. The LEDs are well dissipated into the entire area by the use of heatsinks where more surface area of walls and windows can work on conducting it away. Where as the HPS needs lots of air bombarding it to cool it to the same operating temp as LED and none of that heat is conducted to a heatsink initially so all of it has to be convected. If you don't have this massive amount of air flow the room will not be in equilibrium and you'll have a hot spot around the bulb not allowing all the walls and windows to conduct the heat away because it's still under the light. This massive amount of air needed to be rushed passed a hot object to cool it vs a small amount of air passed over a large surface (heat sink) is the reason for the difference in rates of air temp.
I can't say for certain and am looking into it but I think what's happening between a heatsinked light vs a non heatsinked light has to do with the density of air.
My logic..
Density of air is .075lb/ft3
Density of aluminum is 172lbs/ft3
Specific heat of air is 1ish
Specific heat of aluminum is .9sh
Total mass of air absorbing convective heat from lightbuls is actually pretty small when you convert air into pounds.
If the specific heat capacities of the 2 substances are relatively the same (.9 or 1) but the densities are wildly different, by adding a little bit of aluminum to the room you could possibly double the heat capacity of the room.
The fact that it takes about 2,300 ft3 of air to equal the mass of 1ft3 of aluminum, that the extra heat sink is actually doubling (considering amount of air volume) the heat capacity of the room or reducing much of the air needed to absorb heat as convection. The heatsink will be needed to be eventually convected as well, but this is the difference in rates that I'm talking about.
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WeedSexWeightsShakes
Well-Known Member
So, they will “heat” up a room at different rates. Which makes a huge difference in temps, when it comes to air exchange inside a grow room or tent.
So in a way 1000w isn’t a 1000w when it comes to air exchange and temps. Yes? No?
JSheeze
Well-Known Member
Yep 1000W HPS is going to heat up a grow room faster than 1000w LED, and rooms or tents aren't closed systems so 1000w HPS does NOT equal 1000w LED in terms of air temp in an open system.
hybridway2
Amare Shill
Heres the 4x4 crusher, 1000w hps DE replacement & a serious fixture to contend with. We'll see as the new fixtures for "19". Role out. But this will be hard to beat.
Unfortunately I am not at liberty to disclose the specific spectrum but if you've seen the Equetorial spectrum & liked it this is a combo of the medical curve & the Equetorial. Not sure if they will release it seeing how theres so much time in tuning & testing on crops to just give it away like last time. They don't just randomly toss colors together or just add a lil 660 n call it a day.
At 36" it beats a 1000w hps big hood @2' using 660w & can be used as close as 6" or bump it up to 880w & cover a 5'x5' @ 18".
Unfortunately I am not at liberty to disclose the specific spectrum but if you've seen the Equetorial spectrum & liked it this is a combo of the medical curve & the Equetorial. Not sure if they will release it seeing how theres so much time in tuning & testing on crops to just give it away like last time. They don't just randomly toss colors together or just add a lil 660 n call it a day.
At 36" it beats a 1000w hps big hood @2' using 660w & can be used as close as 6" or bump it up to 880w & cover a 5'x5' @ 18".
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Yodaweed
Well-Known Member
The heatload is the same however the areas that are heated are different.
HPS has a lot of IR so it will heat the floor and walls faster, LEDs blow heat out of their heatsinks so they radiate heat upwards.
But nevertheless if the area is enclosed the heatload will be the same .
JSheeze
Well-Known Member
That is one mighty thick skull you have lol
HPS of equal wattage will heat up a room faster even if the room is circulated from top to bottom. The fact that they produce more heat intially, ie less effecient than LED means they will heat up surrounding areas faster.
If you were to somehow build a closed system, the time it took the light to be absorbed and transformed into thermal would be less of an impact on the total system over time versus the thermal produced initially from the two types of light given their different efficiencies. If you powered those closed systems for an hr and then waited for an extended period of time for all the energy to equalize or all the heat to dissipate over the entire closed system, then yes after the power has been cut and after the HPS has been given time to distribute its energy evenly throughout the walls because its a CLOSED system they will be observed at the same temp. But tent walls conduct heat. Not closed system. Room walls conduct heat. Not closed system. At the rate light is transformed into thermal, I'm telling you, it's conducted away via the walls just as fast. The issues people are dealing with is the convection heat from operating temps of the lightbulbs and tech. I've gone over this with experts in the field, real life experts lol not opinions from threads on the internet. This is fact. Grow tents aren't closed systems. And for the UK folks...
Rates bloody matter! Haha
Yodaweed
Well-Known Member
what do you not understand ?1000w of any light is 3412 BTU of heat...for fuck sakes dude stop.
JSheeze
Well-Known Member
what do you not understand ?1000w of any light is 3412 BTU of heat...for fuck sakes dude stop.
Rates lives matter
Why we don't use 1000w LEDs to heat our houses. It takes a lot less time to heat something using a device that has most of its power converted into heat initially than something that doesn't,.. say... A space heater vs an LED lol
Do you line your tents with concrete? Oh, you mean they paper thin? And conduct heat? Crazy...
Rates matter
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JSheeze
Well-Known Member
How much light is absorbed by the air? Not much?, k. How much is air temp effected by PAR radiation? Not much?, k. What are we concerned about? air temp? Ok so how much convection that HPS put off, mhm, k, and how much convection that LED put off, mhm, k, well i think I got all my answers..
Wait wait gotta couple more q's...
How efficient is heat transfer via radiation? Oh, the slowest?, k. How are HPS cooled? Oh, convection?, k. How is air heated? Oh, convection?, that's crazy!, but ok.
Wait wait gotta couple more q's...
How efficient is heat transfer via radiation? Oh, the slowest?, k. How are HPS cooled? Oh, convection?, k. How is air heated? Oh, convection?, that's crazy!, but ok.