Help improve my setup/growing practices

Stilg7 said:

I'm starting to look into the IR's and PPFD meters. Are these needed if I have a PAR meter already? Do I need to spend big money on them? Any and all information I can get about these before I buy (if even needed) would be greatly appreciated.

Click to expand...

If you've spent the $$ on a PAR meter, that's a big first step. Your PAR meter measures PPFD . PAR (photosynthetically active radiation) means the different wavelengths (colors) of light (even though light is photons?) that plants use for photosynthesis. The range of wavelengths that are included in PAR has increased at the high and low ends over the past few years as research has discovered that plants can take advantage of those wavelengths.

IR is at the high end of the PAR spectrum and grow light manufacturers are incorporating IR LED's in their lights, as well as offering lights that are IR-only. You've got to dig around a bit to get much info on IR and, unless you're going to really geek out on light and are looking for a reason to spend $$, I wouldn't concern myself with an IR meter.

There are tons of resources on all of this. This one (picked at random)lays things out pretty well. The PPFD values from your PAR meter can be used to figure out the DLI (daily light integral = the amount of photons that your plants are receiving over the course of a day). Another use is to figure out how deal with an uneven canopy - my current grow has plants at 20", 30", and 40" so I titled the light pretty seriously to try to get the right light levels.

This page has a commonly used DLI chart and this is one shows how much light cannabis should have at a given stage of growth. I haven't seen any data backing up that chart. The only data-backed research that I've seen is from Dr. Bugbee. His videos are available on YouTube but I've attached one of his research papers along with a separate attachment that is the main chart from the paper about PPFD and cannabis. There's also an easy to read reference graphic that helps explain things.

Re. the chart below shows photosynthesis at different temperatures and different PPFD levels. 25° C is 77°F and it shows that you can really pour on the light and cannabis keeps on growing. There's more to it than just lots of photons, though, Bugbee explains all of this, and more, in his videos.

Stilg7 said:

Thank you for that information. Do you think I need a PAR meter? Maybe I'd be ok with just a IR meter with my lux meter? Here is the lux meter I have-Amazon product

Click to expand...

"need" - no. A lot of growers have produced huge amount of great herb using the "Keep the light 18" above the canopy". In terms of priority of purchasing things, I'd prioritize it pretty much at the bottom of the list.

"IR meter"- IR light is a tiny portion of the PAR spectrum. Until a few years ago, it wasn't even recognized to be part of the PAR spectrum so, even if you could find a legit IR meter, I'd pass.

A lux meter measures light across the spectrum of the human eye. That's a much wider spectrum of light than a PAR meter but some manufactures publish data that allows you to convert LUX to PPFD. Check with the company that makes your grow light.

There is an iOS app (I think it's on Android now), called Corona//Photone. "Corona" was the old name but they changed it for some reason… Having tested the app on my iPhone XS Max (older model) I would recommend Photone over a luxmeter. Photone will get you pretty close; a lux meter measures a lot of light that plants don't use.

Delps8 said:

"need" - no. A lot of growers have produced huge amount of great herb using the "Keep the light 18" above the canopy". In terms of priority of purchasing things, I'd prioritize it pretty much at the bottom of the list.

"IR meter"- IR light is a tiny portion of the PAR spectrum. Until a few years ago, it wasn't even recognized to be part of the PAR spectrum so, even if you could find a legit IR meter, I'd pass.

A lux meter measures light across the spectrum of the human eye. That's a much wider spectrum of light than a PAR meter but some manufactures publish data that allows you to convert LUX to PPFD. Check with the company that makes your grow light.

There is an iOS app (I think it's on Android now), called Corona//Photone. "Corona" was the old name but they changed it for some reason… Having tested the app on my iPhone XS Max (older model) I would recommend Photone over a luxmeter. Photone will get you pretty close; a lux meter measures a lot of light that plants don't use.

Click to expand...

Couldn't agree more on Photone - I use the same app and after having seeing multi-point tests, etc, the app reading is very close to expensive PAR meters. It is available for the iPhone too.

_state_of_mind_ said:

Couldn't agree more on Photone - I use the same app and after having seeing multi-point tests, etc, the app reading is very close to expensive PAR meters. It is available for the iPhone too.

Click to expand...

I just gave that Photone a try and it works as well as the PPFD one I've tried. Both useless with the numbers jumping all around so much as to be meaningless. I don't have any way to calibrate either but regardless of that the numbers should stay steady and no swing from near zero to the hundred or thousands depending on units being used.

I get more usable info from the cheapo light meter on my $12 3-in1 probe.

LabRat said:

I just gave that Photone a try and it works as well as the PPFD one I've tried. Both useless with the numbers jumping all around so much as to be meaningless. I don't have any way to calibrate either but regardless of that the numbers should stay steady and no swing from near zero to the hundred or thousands depending on units being used.

I get more usable info from the cheapo light meter on my $12 3-in1 probe.

Click to expand...

Did you use a diffuser? It's a must. An easy hack to make a quick diffuser - take a coke bottle cap and cut open the top, and stick a circular piece of plain printing paper. That's it, you get very consistent readings with no jumps. I have measured multiple times at multiple places and the readings have been accurate.

Here is a video describing the process -

_state_of_mind_ said:

Did you use a diffuser? It's a must. An easy hack to make a quick diffuser - take a coke bottle cap and cut open the top, and stick a circular piece of plain printing paper. That's it, you get very consistent readings with no jumps. I have measured multiple times at multiple places and the readings have been accurate.

Here is a video describing the process -

Click to expand...

Later he says just to use the paper flat on the sensor but shows his testing with the diffuser.

My first screen was this with my diffuser that was just like his.



Hard to get a pic without the reflection but I can do it when I'm more awake and not getting legless from the RSO I took with some ice cream an hour ago.

This is no diffuser 22" under my 600w Hortilux SHPS which I think is too much for the plants as all the bigger leaves are going lighter green while ones shaded or further from the light are still dark green. Going to switch it out for a 400 tomorrow. Only a 3x3' ScroG area to cover so the 400 will be enough now that they are just over 4 weeks 12/12. I used to get good buds using a 400 to cover 5x5' so the 600 is a bit of overkill and costing me more methinks.



With the diffuser. Big difference in numbers. My little light meter only reads to 2000 and at this spot the needle is buried. Barely under 2000 when dimmed to 50% and I know I get great growth with the needle around 1000. No idea what it's units are but still handy to check how intense the light it at different heights or spots around the canopy. I gives steady readings so is at least comparable with different lights as to intensity but not light quality but with a Hortilux I can safely assume it's good light.



I'll have to experiment some more under controlled conditions to get a better feel for it and what the numbers mean to me. The other app for this, called PPFD Meter, rates your reading poor - fair- good - excellent so at least there I have an idea where I'm at.

Not tonight tho.

Thanks for the video!

Looking at my pic with the diffuser it looks like it slipped down and maybe the plastic rim which is pretty thick might be over the light sensor. Wish I knew someone close enough that had a PAR meter I could borrow for a couple days.

LabRat said:

Looking at my pic with the diffuser it looks like it slipped down and maybe the plastic rim which is pretty thick might be over the light sensor. Wish I knew someone close enough that had a PAR meter I could borrow for a couple days.

Click to expand...

This is exactly what I thought too. Try to hold the phone flat and keep the front sensor of the phone in the middle of the diffuser cap (not sure if you can use elastic bands, etc to keep it in place. I see 3 sensors on the front of your phone, so make sure your diffuser is placed on the correct sensor. On my iPhone 12, the readings seem pretty accurate.