Important info when purchasing LEDs: understanding PPF and PPFD

MasterMiller

MasterMiller

Well-Known Member
Plant Lobbyist said:
Let's work from there then.

Hydrofarm Quantum Par meter $120.00

Ok how much do you have left? Do you have a tent? Any other spare parts? Can you buy stuff used, eg. Kijjiji, Craigslist?

Grow method? 2 plant scrog? Vert? au naturale?

If you only got around 200 left, check out Cobby for 4 light engine kits and a driver.

If you have a bit more, check out the Timber Kits.

Also consider quantum boards since 2 are about 150.

For color, my preference would be 2700K low CRI and 3000K high CRI, 2 of each. You will get the benefits of >700nm (IR or FR for you cliche wonks) from both. Target for around 50w per cob, lower till you get around 700-800ppfd at the canopy. You will get 'stretch' but I find that it makes the plant more manageable for training, and anecdotally more healthy overall. Shortened flowering time can be from a few days up to a couple of weeks for lengthy strains.

Now if you can pick up a used chinese fixture cheap and are willing to upgrade it, that will save you on driver and heatsinks. Most of the drivers in the chinese fixtures will run CoBs just fine and have enough cooling to dissipate the heat. The more you can save here, the more CoBs you can get. Or a quantum board, they are an even easier replacement.

edit: Oh you already bought stuff. Ok go buy the PAR meter, you are doing fine. The meter will help you best position all of your lights in your grow space.
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if you go to my grow journal it kind of explains what I'm working with.
 
MasterMiller

MasterMiller

Well-Known Member
Plant Lobbyist said:
I don't know about that. A ph meter used to be essential but with organics, I don't see a use for it anymore.

I think for beginners it does explain a lot for them. Old people get it too - they are the best gardeners. Once they overcome the initial learning curve they become experts on light.

Growing knowledge is still most important. Light is only one aspect.
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I completely agree. Pretty much from all my research and personal experience grower patience and talent are a huge part of growing anything. In this day and age tho more is always better is the motto and in gardening I come to see less is mucuuuch better. Not saying light isn't a big factor.
 
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Plant Lobbyist

Well-Known Member
MasterMiller said:
if you go to my grow journal it kind of explains what I'm working with.
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It says I can't view it so you probably don't have it public.

But you should still get a PAR meter. Its kind of like a tire pressure gauge for your car. You can survive without one but it is very handy and can help you get things balanced out.
 
MasterMiller

MasterMiller

Well-Known Member
Plant Lobbyist said:
It says I can't view it so you probably don't have it public.

But you should still get a PAR meter. Its kind of like a tire pressure gauge for your car. You can survive without one but it is very handy and can help you get things balanced out.
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It takes about 48 hours for you to view that stuff I got the same thing when I first started
 
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Plant Lobbyist

Well-Known Member
If we were playing 'LP Tycoon' and had a $300 starting budget I would get:

5 buckets (25)
PAR meter (120)
12 pack of ecosmart 2700k CCT (50)
Shovel (5)
12 slot power bar (25)
12 socket adapters (50)
5 pack of good genetics (25)

Take my chances on the genetics and go with regular, non-femmed to live on the danger side. Forget the timer, use your alarm clock.
 
MasterMiller

MasterMiller

Well-Known Member
I figure once I get 10 successful grows under my belt I will start pheno hunting. That's really what I want to do but I wanted to learn how to grow and at least have a 70 to 80 chance of getting something from only two plants vs 50/50 chance on two plants. I'm on my third flower cycle and I have two almost ready to go into flower, with two more 39 days from seed and 2 more I just planted yesterday.
 
MasterMiller

MasterMiller

Well-Known Member
Perfect timing cause I ordered that timber kit and should get it when the new guys pop. That will be a whole grow from seed to harvest from a new grower using citizen clu048 1212. I'm excited to see the results compared to my P300's
 
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Plant Lobbyist

Well-Known Member
MasterMiller said:
I figure once I get 10 successful grows under my belt I will start pheno hunting. That's really what I want to do but I wanted to learn how to grow and at least have a 70 to 80 chance of getting something from only two plants vs 50/50 chance on two plants. I'm on my third flower cycle and I have two almost ready to go into flower, with two more 39 days from seed and 2 more I just planted yesterday.
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These days you will probably never get to that point. There is too much selection out there for genetics and once you get dialed in, you will want to try and grow everything. Plus you will see how much work it is to grow and your enjoyment will dwindle.

My suggestion would be to start looking at the genetics you would want to run in the future and hunt them down.
 
MasterMiller

MasterMiller

Well-Known Member
Yup. I'm actually looping back around cause my first grow was hso Bubba'sGift and the seeds I just planted are Bubba's Gift. I want to run a couple more of there fem seeds and then I want to actually get into land races
 
wietefras

wietefras

Well-Known Member
cdgmoney250 said:
Knowing the light spread of different fixtures at different distances is definitely useless information....
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The problem is taht it's only measuring part of the total light. So yes, what's the point?

For instance, for HPS it's usually only half the light that falls inside that measuring square.
 
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MasterMiller

MasterMiller

Well-Known Member
For the small timers like me, having those tools really isn't probable due to money, but for someone with a big budget or a commercial company with big pockets those tools would be clutch.
 
cdgmoney250

cdgmoney250

Well-Known Member
wietefras said:
The problem is taht it's only measuring part of the total light. So yes, what's the point?

For instance, for HPS it's usually only half the light that falls inside that measuring square.
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I understand what you are saying. Light manufacturers should make their 'PAR Charts' large enough to capture all of the light until the meter reads zero. I feel that this should be done in an open area with NO reflectivity so we know just what kind of footprint is being laid down. Reflective walls are the duty of the grower, IMO.

It would be nice to test 2-4 identical fixtures in an open area spaced out to get even light distribution between them. This would give growers an idea of how far apart their lights would need to be, and how many fixtures would be needed to cover a larger area of canopy. Doing this would provide real world numbers growers could use as a reference for their specific application.

Edit: Perhaps light manufacturers should test their fixture in an open area and in a tent. This would show the performance of their light dependent on how the grower chose to run them.
 
MasterMiller

MasterMiller

Well-Known Member
cdgmoney250 said:
I understand what you are saying. Light manufacturers should make their 'PAR Charts' large enough to capture all of the light until the meter reads zero. I feel that this should be done in an open area with NO reflectivity so we know just what kind of footprint is being laid down. Reflective walls are the duty of the grower, IMO.

It would be nice to test 2-4 identical fixtures in an open area spaced out to get even light distribution between them. This would give growers an idea of how far apart their lights would need to be, and how many fixtures would be needed to cover a larger area of canopy. Doing this would provide real world numbers growers could use as a reference for their specific application.

Edit: Perhaps light manufacturers should test their fixture in an open area and in a tent. This would show the performance of their light dependent on how the grower chose to run them.
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I wanted to do this as a way to test lights but it would cost a fortune and the space needed isn't probable
 
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Plant Lobbyist

Well-Known Member
MasterMiller said:
I wanted to do this as a way to test lights but it would cost a fortune and the space needed isn't probable
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All that matters is the PAR reading you get from the meter at the spot(s) your plant is growing.

weitefras is special in that he thinks photons gain magical powers when they bounce off shiny things.

Just get the meter and stop the guesswork. You will feel better once you do and can get on to cooler things such as VPD.
 
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Plant Lobbyist

Well-Known Member
visajoe1 said:
check out my post for a DIY par meter

https://www.rollitup.org/t/diy-par-meter-30-45.932412/
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Only criticism I have with that is the bias towards the blue region. Accuracy and calibration aside, it is good thinking out of the box. Those lux meters are just counters for a sensor and you have essentially swapped out the sensor.

As more people start growing the price for PAR meters will drop to reasonable levels eventually. They really don't need to be anymore expensive than a lux meter.
 
wietefras

wietefras

Well-Known Member
cdgmoney250 said:
I understand what you are saying. Light manufacturers should make their 'PAR Charts' large enough to capture all of the light until the meter reads zero. I feel that this should be done in an open area with NO reflectivity so we know just what kind of footprint is being laid down. Reflective walls are the duty of the grower, IMO.

It would be nice to test 2-4 identical fixtures in an open area spaced out to get even light distribution between them. This would give growers an idea of how far apart their lights would need to be, and how many fixtures would be needed to cover a larger area of canopy. Doing this would provide real world numbers growers could use as a reference for their specific application.

Edit: Perhaps light manufacturers should test their fixture in an open area and in a tent. This would show the performance of their light dependent on how the grower chose to run them.
Click to expand...
Sorry, but there really is no point for these matrices in real life.

How far the lights need to be apart depends for instance on desired light intensity and on what height the fixtures will be above the plants. These are not fixed, but variables that will differ per grower and per type of plant.

If you want a PPFD of about 800umol/s/m2, how would you use such a matrix anyway? What you would do is see how much light the fixture produces and (perhaps after deducting some wall losses) divide that by 800 to get the surface area in m2 you can cover with that fixture. That's exactly what we do with the COBs too. Why would that be different for whole fixtures?

The matrix would need to be massive to measure all the light from an HPS fixture. They will easily light a circle with a 5 meter radius. Remember these things are built to be used in huge greenhouses or to light up roads.

Instead of these error prone spot measurement matrices, professional light manufacturers provide an isodiagram. This shows the actual light distribution for the fixture and those you can actually use in software to calculate light distributions.

Like this one for the Gavita Pro with HR96 reflector:
HR96.jpg
For COBs we also get these things from the manufacturer. They are usually in the datasheet.
 
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