Bud2theBone
Active Member
I’m sort of confused with the lights. If I use MH to veg and HPS to flower...I somewhat have the hps figured out but how do I calculate the wattage of the MH I’ll need?? I have a 5x5 space and a 2x2 space
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Bud2theBone
Active Member
I have t5s already but everybody says the MH is better suited. Plus I’m not even entirely sure of my t5 wattage as I was a dumb newbie just buying lights
kingromano
Well-Known Member
t5 are for young plant .. then you veg them under the mh
as soon as they flower just hang 1000w hps at 4/5ft over this 5x5
400W=3x3
600w=4x4
1000W=5x5
as soon as they flower just hang 1000w hps at 4/5ft over this 5x5
400W=3x3
600w=4x4
1000W=5x5
ChiefRunningPhist
Well-Known Member
Photons are particles of light. If there's light, it's because light particles, or photons are present.
Just like shoes come in all sizes, photons come in all different energy levels. Energy is labeled in Joules. Joules, or J's, are units of energy. There's low energy photons (red), high energy photons (violet), middle energy photons (green), and all sorts in between. The photon energy level is dependent on it's wavelength and visa versa. This means that if you know the photon energy level, you also then know it's wavelength, likewise if you know that a certain wavelength of light is present, you would also then know the energy level of those photons being emitted. The terms "wavelength" and "photon energy" are like "RPM" and "MPH", with one of these pieces of data, you can determine the other. For every wavelength there's a corresponding photon energy, and for every photon energy there's a corresponding wavelength.
Wavelength ÷ 119.6 = μmol/J
119.6 ÷ Wavelength = J/μmol
119.6 ÷ J/μmol = Wavelength
119.6 × μmol/J = Wavelength
Light particles are tiny. The human eye can't detect increments that small. We weigh our produce at the checkout line in pounds, we don't try to count up all the individual molecules creating the produce, that would be crazy! Its the same for light, we pool photons together in groups and then count the number of groups. These groups are a big number. 602,214,090,000,000,000 photons make up 1 group. The groups are called micro-moles, and each group is labeled as μmol. μmol only tells how many photons are present, μmol is a term of quantity, it has nothing to do with the energy of the photons, only how many there are.
(If you remember Avagadros constant from chemistry, that's where the term mole comes from. A micro mole is a mole that's been divided by 1 million)
Plants need photons to grow. They use different energy photons for different plant processes, or they use different wavelengths of light for different plant processes. For example, far red light (730nm, or 0.163J/μmol, or 6.1μmol/J, all the same thing, just using different terminology) causes the plant to stretch, while UVB (285nm, 0.419J/μmol, or 2.38μmol/J) light induces a response that causes the plant to produce more trichomes (and THC).
When it comes to determining light needs, you'd want to understand how many photons the plant wants, and what energy level it wants the photons to be at, per the given stages of its life (seedling, veg, bloom).
The amount of photons needed is pretty well documented, but the energy level or wavelengths needed is a bit more ambiguous. It's what's being studied atm. So if we disregard the wavelengths necessary for the time being, and just focus on the quantity, you can then calculate ball park needs fairly easily.
MH & HPS put out about 2.0μmol/J each. This means that it takes 1 joule of energy input, and the light outputs 2μmols of photons. Depending on the stage of growth you're on and your vegetation footprint, a wattage can be calculated.
According to Fluence Bioengineering, the cannabis seedling stage requires 100-300μmol/s·m2, the cannabis vegetation stage requires 300-600μmol/s·m2, and the cannabis bloom stage requires 600+μmol/s·m2.
μmol/s·m2 means the number of micromoles of photons, being emitted every second, in an area that's 1 meter squared, PPFD = μmol/s·m2, they are the same thing.
10.76ft2 = 1m2
5'×5' = 25ft2
25ft2 ÷ (10.76ft2/m2)
=
2.32m2
2'×2' = 4ft2
4ft2 ÷ (10.76ft2/m2)
=
0.37m2
Lets say you're wanting to veg with a MH. Let's assume you're looking to achieve 300PPFD, or 300μmol/s·m2. Most HID are ~2.0μmol/J, or 2.0μmol per watt.
1W = 1J/s; watts are the amount of joules measured per second.
(300μmol/s·m2) ÷ (2.0μmol/J)
=
150J/s·m2; 150W per m2 of MH.
2 areas:
2.32m2 × 150W/m2 = 348W
0.37m2 × 150W/m2 = 55.5W
If you understand this you can apply it to any grow room and any light. You just need the μmol/J of the particular light being used, the grow area, and a target PPFD for that area, or a target μmol/s·m2 for that area. I'd reccomend 850PPFD as max for bloom stage without CO2 being added.
Just like shoes come in all sizes, photons come in all different energy levels. Energy is labeled in Joules. Joules, or J's, are units of energy. There's low energy photons (red), high energy photons (violet), middle energy photons (green), and all sorts in between. The photon energy level is dependent on it's wavelength and visa versa. This means that if you know the photon energy level, you also then know it's wavelength, likewise if you know that a certain wavelength of light is present, you would also then know the energy level of those photons being emitted. The terms "wavelength" and "photon energy" are like "RPM" and "MPH", with one of these pieces of data, you can determine the other. For every wavelength there's a corresponding photon energy, and for every photon energy there's a corresponding wavelength.
Wavelength ÷ 119.6 = μmol/J
119.6 ÷ Wavelength = J/μmol
119.6 ÷ J/μmol = Wavelength
119.6 × μmol/J = Wavelength
Light particles are tiny. The human eye can't detect increments that small. We weigh our produce at the checkout line in pounds, we don't try to count up all the individual molecules creating the produce, that would be crazy! Its the same for light, we pool photons together in groups and then count the number of groups. These groups are a big number. 602,214,090,000,000,000 photons make up 1 group. The groups are called micro-moles, and each group is labeled as μmol. μmol only tells how many photons are present, μmol is a term of quantity, it has nothing to do with the energy of the photons, only how many there are.
(If you remember Avagadros constant from chemistry, that's where the term mole comes from. A micro mole is a mole that's been divided by 1 million)
Plants need photons to grow. They use different energy photons for different plant processes, or they use different wavelengths of light for different plant processes. For example, far red light (730nm, or 0.163J/μmol, or 6.1μmol/J, all the same thing, just using different terminology) causes the plant to stretch, while UVB (285nm, 0.419J/μmol, or 2.38μmol/J) light induces a response that causes the plant to produce more trichomes (and THC).
When it comes to determining light needs, you'd want to understand how many photons the plant wants, and what energy level it wants the photons to be at, per the given stages of its life (seedling, veg, bloom).
The amount of photons needed is pretty well documented, but the energy level or wavelengths needed is a bit more ambiguous. It's what's being studied atm. So if we disregard the wavelengths necessary for the time being, and just focus on the quantity, you can then calculate ball park needs fairly easily.
MH & HPS put out about 2.0μmol/J each. This means that it takes 1 joule of energy input, and the light outputs 2μmols of photons. Depending on the stage of growth you're on and your vegetation footprint, a wattage can be calculated.
According to Fluence Bioengineering, the cannabis seedling stage requires 100-300μmol/s·m2, the cannabis vegetation stage requires 300-600μmol/s·m2, and the cannabis bloom stage requires 600+μmol/s·m2.
μmol/s·m2 means the number of micromoles of photons, being emitted every second, in an area that's 1 meter squared, PPFD = μmol/s·m2, they are the same thing.
10.76ft2 = 1m2
5'×5' = 25ft2
25ft2 ÷ (10.76ft2/m2)
=
2.32m2
2'×2' = 4ft2
4ft2 ÷ (10.76ft2/m2)
=
0.37m2
Lets say you're wanting to veg with a MH. Let's assume you're looking to achieve 300PPFD, or 300μmol/s·m2. Most HID are ~2.0μmol/J, or 2.0μmol per watt.
1W = 1J/s; watts are the amount of joules measured per second.
(300μmol/s·m2) ÷ (2.0μmol/J)
=
150J/s·m2; 150W per m2 of MH.
2 areas:
2.32m2 × 150W/m2 = 348W
0.37m2 × 150W/m2 = 55.5W
If you understand this you can apply it to any grow room and any light. You just need the μmol/J of the particular light being used, the grow area, and a target PPFD for that area, or a target μmol/s·m2 for that area. I'd reccomend 850PPFD as max for bloom stage without CO2 being added.
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PadawanWarrior
Well-Known Member
How long are your t5's? Cause if you can fit them in the 2x2, that would be decent for veg, but MH or quality LED's would probably kick its ass if you have the height for them.
diggs99
Well-Known Member
Nice to see you Chief,
im not sure ive ever read a post of yours that i havent learned something.
Op....If using hps for flowering you want to be around 50/60watts per ft2
For vegging its not nearly as important, you can get away with much less wattage, basically during veg you want good coverage more than crazy power.
T5s rock for veg up to a certian size plant, if i want to grow and train lower bushy girls id use my t5s for as long as i could, until they outgrew the lights. MH vegs plants nice too , so you got all you need to grow some dank.
As @PadawanWarrior suggested, if you can fit the t5s in the 2x2 id probably do that and a 600w MH for vegging a full canopy 5x5
Or as @f series said, buy leds lol
Bud2theBone
Active Member
LED a little tricky I’m new to it so I’m trying to do it the simplest way possible. But I’m sure this grow will be better than my 1st. You guys pretty much covered everything I made mistakes on. It’s definitely appreciated
coreywebster
Well-Known Member
600w MH will do, 1000w MH will do it faster.