Are these par meters worth it

[freezeland2]

Honestly run the light at max if possible and adjust height would be the best way to go.

I dont see a need for any such device. It doesn’t tell you what a plant can handle and every single grow and genetic is different.

They are meant to record readings that can be duplicated later on. You can do that with any meter. Its just not as universally accurate when giving data to someone else

Any thoughts on my post #77

 

[Aqua Man]

View attachment 1256222

their chart is a little confusing, but the actual comparison line is almost 100% in line with the non-dimmed light :)

Better picture:

View attachment 1256224

Not sure what you are circling i am talking about the difference in this area.

 

[Observationist]

1st pic 600w hps at 26" with open reflector. 2nd 600rspec. The hps looks more natural to me. May just be me, under the Rspec the nodes are stacked decent but the new growth looks thin compared to hps

Just lower a few inches

 

[Aqua Man]

I have been resisting replying to this thread as I too have an Apogee. I use it everyday and have 3 plants beginning flowering. They are two different strains so I have them in two separate spaces. What I find useful with my apogee and has been very educational is the correlation between the response to lighting and vpd. There are days when the plants want more light, and other days less light. And vpd plays a huge role in that. I have been recording my ppfd readings and vpd when I have the leafs presenting flat. When I see or intentionally make changes in vpd I have recorded readings so I know exactly what intensity I need to set the light at. It’s amazing to watch the plants respond. Before it was all guess work, not now.

Thats exactly the point i was making the meter is great for record purpose’s. Because every grow room and genetic is different. The meter allows a reference but it cannot tell you how much light your plants need. You can do the same with a cheap meter so long as it’s consistent.

Then if you give your measurements to someone with the same meter they can use it as a guide but really only to a point because they are different rooms and genetics. So really any consistent meter will allow you this.

You are 100% accurate that VPD will affect this. And so does everything else, the higher the plants tolerance to light the more efficient you have made photosynthesis by changing whatever parameters you did

 

[Aqua Man]

So long story short is dimmers are not really beneficial and running your light on max gives you the intended spectral ratios the manufacturer designed it for in most cases

Adjusting the height gives your your intensity and also spread. Which is why bar/strip light leds are so beneficial. Because they can be run at max power closer with a more even spread leading to less wasted photons while maintaining the intended spectrum.

I really need to sit down one day and write all this out so i can just link a thread… what can i say im lazy

 

[Blastfact]

The way HLG does there dimmers and driver programing is very flat concerning spectrum. And there is no magic sauce being hidden from anybody or the light spectrum with the last two dimmer settings. If you map out your watts draw and have a EPAR MQ-610 and a MQ-500 the 610 will show a higher PPFD dimmers wide open because it's sensing some of the UV and the scant amount of far red the 500 cant measure. With my 260 rspecs and 350r's I have tested them with a spectrum tool much like MIGRO has used in his video's. And a 500 and my 610. To replicate HLG's spectrum chart one has to be wide open on the dimmers and as you bring the dimmers down you lose a very small bit on the UV and far red and a bit on your total curve. But in the big picture it's only maybe 3% to 4% between max settings and the lowest setting. So the over all spectrum change is very very little over all between idle and max power. It's really miniscule. It's funny to see how a 610 will measure the UV and far red better than the 500. Wide open the 610 will read 20 or maybe 30 higher on the PPFD and as you bring the dimmers back down the two meters start reading closer to the same because the edge of the UV and far red the 610 EPAR can see starts going away.

 

[Aqua Man]

The way HLG does there dimmers and driver programing is very flat concerning spectrum. And there is no magic sauce being hidden from anybody or the light spectrum with the last two dimmer settings. If you map out your watts draw and have a EPAR MQ-610 and a MQ-500 the 610 will show a higher PPFD dimmers wide open because it's sensing some of the UV and the scant amount of far red the 500 cant measure. With my 260 rspecs and 350r's I have tested them with a spectrum tool much like MIGRO has used in his video's. And a 500 and my 610. To replicate HLG's spectrum chart one has to be wide open on the dimmers and as you bring the dimmers down you lose a very small bit on the UV and far red and a bit on your total curve. But in the big picture it's only maybe 3% to 4% between max settings and the lowest setting. So the over all spectrum change is very very little over all between idle and max power. It's really miniscule. It's funny to see how a 610 will measure the UV and far red better than the 500. Wide open the 610 will read 20 or maybe 30 higher on the PPFD and as you bring the dimmers back down the two meters start reading closer to the same because the edge of the UV and far red the 610 EPAR can see starts going away.

It is in an overall sense but when you look at the impacts a very tiny amount of UV and infared make in plant photomorphology its not as minuscule as led to believe. Especially when a 5% uvb can stress plants right the fuck out as seen when we move indoor plant’s outside. They need to be hardened off first.

So while i agree in theory overall not a big deal but in practice it can make a difference

 

[Aqua Man]

Just to point out the added UV and IR are in tiny amounts to begin with… effectively probably only 5% or less of the overall spectrum. And thats where your 3-4% are being lost.

These spectrums are not there for photosynthesis, they are for photomorphological advantages like increased cannabinoids, terpenoids, flavonoids, manipulation of structure etc.

But your right they have minuscule effect on photosynthesis

 

[Blastfact]

It is in an overall sense but when you look at the impacts a very tiny amount of UV and infared make in plant photomorphology its not as minuscule as led to believe. Especially when a 5% uvb can stress plants right the fuck out as seen when we move indoor plant’s outside. They need to be hardened off first.

So while i agree in theory overall not a big deal but in practice it can make a difference

The UV we are losing is "A" as expressed in there own spectrum charts in "nm" same with the Red. When hardening plants for outdoor the UVA in most cases isn't as much as a supplemental UVA light can do. And what gets them is UVB and that can be a real sombitch. And few if any grow lights really put out any real amount of UVB because it destroys leds,,,, very hard for leds to stay whole and put out meaningful UVB in the long run. And the amount of UVA/B some of our older tech puts out like MH/CMH UV is what truly wears them out. It really gets to be a very complex conversation that functions on basic light spectrum and tech thats been around as long as electricity.

 

[Aqua Man]

The UV we are losing is "A" as expressed in there own spectrum charts in "nm" same with the Red. When hardening plants for outdoor the UVA in most cases isn't as much as a supplemental UVA light can do. And what gets them is UVB and that can be a real sombitch. And few if any grow lights really put out any real amount of UVB because it destroys leds,,,, very hard for leds to stay whole and put out meaningful UVB in the long run. And the amount of UVA/B some of our older tech puts out like MH/CMH UV is what truly wears them out. It really gets to be a very complex conversation that functions on basic light spectrum and tech thats been around as long as electricity.

Yes effective and efficient UVB come from fluorescent tubes.

 

[Aqua Man]

I get what you are saying and i don’t disagree. Generally best practice is run at max for the intended spectrum. The spectral ratios change with intensity and that does have an effect on the structure of a plant. Even excluding the UV and IR. This has been shown in the slight difference in just the red, blue and green spectrums of par

IR is more impactful than UV when it comes to the outside par ranges for morphological effects. I was just explaining why the ppfd does not line up to the potentiometer setting.

 

[Moe.Red]

I've got 2 Raging Kush 2 lights arriving today. They state that you can adjust each spectrum individually without loss of power / ppfd. So for example, the blue channel has it's own driver, same with far red, uv, etc. I can see this as a huge advantage in understanding what does what exactly and being able to say tune blue at 1500PPDF or switch to Red leaning, but still at 1500 PPFD. Have some real control over Veg / Flower spectrums.

I can't wait. Friggin christmas in june!

But yeah UVB does not come from LEDs except for maybe a few seconds until they burn up.

I've got an Apoge Par/Far REd that does the typical visible spectrum PPFD and then a 2nd sensor for Far Red you get to with a switch. I think I spent $600 or so a few years ago? If I had it to do over again I still would, but if budget constrained I would advise against it.

 

[Aqua Man]

A really good read on the subject.

Frontiers | An Update on Plant Photobiology and Implications for Cannabis Production

This review presents recent developments in plant photobiology and lighting systems for horticultural crops, as well as potential applications for cannabis (...

www.frontiersin.org

 

[Moe.Red]

A really good read on the subject.

Frontiers | An Update on Plant Photobiology and Implications for Cannabis Production

This review presents recent developments in plant photobiology and lighting systems for horticultural crops, as well as potential applications for cannabis (...

www.frontiersin.org

Wow

In cannabis plants, THC levels are negatively affected by the presence of green light

Magagnini, G., Grassi, G., and Kotiranta, S. (2018). The effect of light spectrum on the morphology and cannabinoid content of Cannabis sativa L. Med. Cannabis Cannabinoids 1, 19–27. doi: 10.1159/000489030

Tons of interesting stuff in that study.

 

[Aqua Man]

Wow

In cannabis plants, THC levels are negatively affected by the presence of green light

Magagnini, G., Grassi, G., and Kotiranta, S. (2018). The effect of light spectrum on the morphology and cannabinoid content of Cannabis sativa L. Med. Cannabis Cannabinoids 1, 19–27. doi: 10.1159/000489030

Tons of interesting stuff in that study.

At above certain ratios

 

[Moe.Red]

No no no… at certain ratios only

Take another look, that was a cut and paste from the study, not me typing that.

Green kinda baffles me to be honest. I don't feel like I have my arms wrapped around that one yet. Conflicting info everywhere unless you really dig in on the details.

 

[Aqua Man]

@Moe.Red lol you have so much to play with now

 

[Aqua Man]

Take another look, that was a cut and paste from the study, not me typing that.

Green kinda baffles me to be honest. I don't feel like I have my arms wrapped around that one yet. Conflicting info everywhere unless you really dig in on the details.

So green is actually the most efficient photosynthetically at high intensity contrary to popular belief.

 

[Moe.Red]

So green is actually the most efficient photosynthetically at high intensity contrary to popular belief.

Yeah man, I learned that from you here

Frontiers | Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms

Red and blue light are traditionally believed to have a higher quantum yield of CO2 assimilation (QY, moles of CO2 assimilated per mole of photons) than gree...

www.frontiersin.org

@Moe.Red lol you have so much to play with now

Impossible.

Edit - I read that as too much to play with. That would be impossible.

 

[Blastfact]

Yes effective and efficient UVB come from fluorescent tubes.

When I worked at a hospital we did a study on UV lighting. In the old days it was standard to bring in special UV lighting for patience care and many rooms had dedicated UV fixtures mounted up high and indirect. It was used to kill some germs and such. What we found out is the UV lights of any type and build available at the time were basically worthless in 30 days running 8 hour light cycles daily. Hospital spent a huge amount of money on this study done with Phillips and in house.