Light intensity

[Purple love]

Whats up everyone question shes about a week into flowering I have her under the mars hydro ts 1000 at 75% light intensity how do I know when to raise it thanks

 

[Delps8]

Unless you're using a meter (lux or PAR), I'd go by the manufacturers recommendations.

In the FAQ, they write:
"In general, our recommended hanging height and dimming settings are as follows: SEEDLING STAGE: Hanging Height: 12"/30cm Dimming Scale: 50% VEGETATIVE STAGE: Hanging Height: 12"/30cm Dimming Scale: 75% However, these are not absolute values and may need to be adjusted based on the specific crop and growth conditions."

At that power setting and hang height, the center of the tent will be at 928µmols which is quite a bit of light but cannabis loves light and, if you run your grow at that setting, you will get a lot of cannabis.

Unless there are problems with the grow, your plants should do very well under that amount of light but I would advise that you increase the amount of light they're getting. What's the hang height now?

 

[Hollatchaboy]

Whats up everyone question shes about a week into flowering I have her under the mars hydro ts 1000 at 75% light intensity how do I know when to raise it thanks View attachment 5342313

 

[secretmicrogrow420]

buy a par meter if you cant afford it buy a lux meter. i currently use the dr.meter led digital lux meter and i love it.

 

[calvin.m16]

100% power and adjust lights to where plants look happy, more on the close side with LED so your not wasting your light.. Learned this moving from HPS to LED the lights need to be wayyyy closer. I keep mine roughly 10-12" from the tops @ 100% power 600-800 watt LEDs multiple fixtures, different brands, no problem.

Environment is usually 75-80 F - 50-55% RH with 400-900 ppm co2 (depending on house occupants, lol)

 

[Purple love]

Unless you're using a meter (lux or PAR), I'd go by the manufacturers recommendations.

In the FAQ, they write:
"In general, our recommended hanging height and dimming settings are as follows: SEEDLING STAGE: Hanging Height: 12"/30cm Dimming Scale: 50% VEGETATIVE STAGE: Hanging Height: 12"/30cm Dimming Scale: 75% However, these are not absolute values and may need to be adjusted based on the specific crop and growth conditions."

At that power setting and hang height, the center of the tent will be at 928µmols which is quite a bit of light but cannabis loves light and, if you run your grow at that setting, you will get a lot of cannabis.

Unless there are problems with the grow, your plants should do very well under that amount of light but I would advise that you increase the amount of light they're getting. What's the hang height now?

Is about 20 inches away from the plant

 

[Purple love]

buy a par meter if you cant afford it buy a lux meter. i currently use the dr.meter led digital lux meter and i love it.

Lol I have that lux app but don't understand it

 

[Jonesfamily7715]

I don't think you could possibly hurt the plants with that light. I'd try to get closer to the 12" %100 range I've seen em almost touch and still be fine at that low of power, the par maps are exaggerated and under perfect conditions, 20" away to far

 

[HydroKid239]

Is about 20 inches away from the plant

Whatever percent you move up on the light, add half that percentage to your feed because it will eat more. I made that percentage up, but don’t it make sense? Lol

On a serious note:
I would still be feeding veg nutes for another week or two before moving to straight bloom feed. Your leaves will thank you later.
I would have that light at 100% by now as well. As close as you can get it without stressing the plant out.
Most ppl won’t lower the light so close, but those are the ones who also feed less (50-75% of the feeding dosage). More light calls for more food, and gets you more yield in the end. Depending on the strain, the difference could be massive.

 

[LeastExpectedGrower]

View attachment 5342320

Love this chart from the Photone people...but the reality is that most users will need either a light-meter app or a light meter to figure out their DLI to get the most from it. I used Photone on my iPhone Xs Max and it proved to be fairly accurate, though I know it's not on some other phones. I have a Phantom Photobio quantum PAR meter that was fairly cheap to use these days, but take that PPFD number and plug it into the DLI calculator on the Photone site to make sure I'm aligning properly.

 

[Hollatchaboy]

Love this chart from the Photone people...but the reality is that most users will need either a light-meter app or a light meter to figure out their DLI to get the most from it. I used Photone on my iPhone Xs Max and it proved to be fairly accurate, though I know it's not on some other phones. I have a Phantom Photobio quantum PAR meter that was fairly cheap to use these days, but take that PPFD number and plug it into the DLI calculator on the Photone site to make sure I'm aligning properly.

I got the same meter, and do the same thing to get my dli.

 

[LeastExpectedGrower]

I got the same meter, and do the same thing to get my dli.

I play a little game of measuring at the tips of the tallest tops then at the 'plain' where most of the rest of the tops are and adjusting so that the tops don't get blasted but the rest of the uppers get the most effective light as well. Takes some futzing, but I can get both zones in the green for most effective light for best growth.

 

[Delps8]

Love this chart from the Photone people...but the reality is that most users will need either a light-meter app or a light meter to figure out their DLI to get the most from it. I used Photone on my iPhone Xs Max and it proved to be fairly accurate, though I know it's not on some other phones. I have a Phantom Photobio quantum PAR meter that was fairly cheap to use these days, but take that PPFD number and plug it into the DLI calculator on the Photone site to make sure I'm aligning properly.

I've tested Photone twice on my iPhone xsMax. The first time was with a blurple. Photone could not provide a value. The diffuser was in place and I had selected the blurple profile. I tested Photone again last summer with a Growcraft X2 and it was consistently 16% high. The fact that it was consistent is good. The fact that it was that high is not.

RE. the chart for Photone - when I was testing Photone, I contacted growlightmeter.com. I've been writing software for a living since the early 90's (second career), mostly running my own business but I did work for Apple for a few years, so I have some insight into the programming problem.

I contacted them because I cannot find anything in "the research" that indicates that light values should be dropped going into flower. Basic plant bio tells us that dropping light levels will tend to decrease growth. Real world research shows that there's an almost linear relationship between light levels and crop quality and yield. With that in mind, I contacted GLM and they stated that the drop in DLI was due to the change in photoperiod. If that was the case, the DLI would not increase after flip. After receiving that reply, I did not pursue that topic any further.

When I inquired about why they recommend a DLI of 45 for autos, the response was that their understanding is that autoflowers can be treated as always being in veg so they recommend a DLI of 45 through the rest of the grow. I was surprised that they take this approach. Unlike the first point, which is simply completely wrong, this second point is…strange. I cannot understand why a company would be giving recommendations with "our understanding is…". That was disappointing and helped me reach the conclusion to not use their products.

When I asked if they had research to support their recommendations, he told me to check the bottom of the web page for citations.

The first tests I did of Photone were using three weights of paper - 20, 22, and 24 pound because, at that time, they did not have a recommendation. As with their recommendations, I was surprised that they didn't specify because using different paper weights gave readings that were 4% to 24% different. That's significant.

The programmer thanked me for my testing and gave me a few sets of year long license keys for all spectra.

I bought an Apogee.

PhotoBio - I've attached a paper from the Apogee site that compares and contrasts PAR sensors. Interesting reading.

I don't recommend Photone unless you have a known good source. That could be meter calibrated to a known good source or to use third party measurements of a grow light. The latter will tend to be less accurate but will be sufficiently accurate.

I am also hesitant to put a $1000 iPhone into a tent and there are usability issues, as well. One of the drawbacks to having the readout in the same device as the sensor is that it limits usability - I can't get a reading at the back of the tent. In contrast, you can use a wand with the Apogee sensor and, with a Unit-T Bluetooth lux meter, the sensor will send the data to a phone.

In addition to an Apogee I bought a Uni-T and that's the approach I would take if I were in the market for a lux meter/PAR meter. The Apogee is an excellent product but at $600 for the sensor + wand, it's not cheap. In contrast, the Uni-T Bluetooth is $32 here in the US and, when used with the correct conversion factor, is, in practical terms, as accurate as an Apogee.

 

[Hollatchaboy]

I've tested Photone twice on my iPhone xsMax. The first time was with a blurple. Photone could not provide a value. The diffuser was in place and I had selected the blurple profile. I tested Photone again last summer with a Growcraft X2 and it was consistently 16% high. The fact that it was consistent is good. The fact that it was that high is not.

RE. the chart for Photone - when I was testing Photone, I contacted growlightmeter.com. I've been writing software for a living since the early 90's (second career), mostly running my own business but I did work for Apple for a few years, so I have some insight into the programming problem.

I contacted them because I cannot find anything in "the research" that indicates that light values should be dropped going into flower. Basic plant bio tells us that dropping light levels will tend to decrease growth. Real world research shows that there's an almost linear relationship between light levels and crop quality and yield. With that in mind, I contacted GLM and they stated that the drop in DLI was due to the change in photoperiod. If that was the case, the DLI would not increase after flip. After receiving that reply, I did not pursue that topic any further.

When I inquired about why they recommend a DLI of 45 for autos, the response was that their understanding is that autoflowers can be treated as always being in veg so they recommend a DLI of 45 through the rest of the grow. I was surprised that they take this approach. Unlike the first point, which is simply completely wrong, this second point is…strange. I cannot understand why a company would be giving recommendations with "our understanding is…". That was disappointing and helped me reach the conclusion to not use their products.

When I asked if they had research to support their recommendations, he told me to check the bottom of the web page for citations.

The first tests I did of Photone were using three weights of paper - 20, 22, and 24 pound because, at that time, they did not have a recommendation. As with their recommendations, I was surprised that they didn't specify because using different paper weights gave readings that were 4% to 24% different. That's significant.

The programmer thanked me for my testing and gave me a few sets of year long license keys for all spectra.

I bought an Apogee.

PhotoBio - I've attached a paper from the Apogee site that compares and contrasts PAR sensors. Interesting reading.

I don't recommend Photone unless you have a known good source. That could be meter calibrated to a known good source or to use third party measurements of a grow light. The latter will tend to be less accurate but will be sufficiently accurate.

I am also hesitant to put a $1000 iPhone into a tent and there are usability issues, as well. One of the drawbacks to having the readout in the same device as the sensor is that it limits usability - I can't get a reading at the back of the tent. In contrast, you can use a wand with the Apogee sensor and, with a Unit-T Bluetooth lux meter, the sensor will send the data to a phone.

In addition to an Apogee I bought a Uni-T and that's the approach I would take if I were in the market for a lux meter/PAR meter. The Apogee is an excellent product but at $600 for the sensor + wand, it's not cheap. In contrast, the Uni-T Bluetooth is $32 here in the US and, when used with the correct conversion factor, is, in practical terms, as accurate as an Apogee.

I can't find where they talk about the photobio.

My problem is, it's a paper written by employees of apogee. I mean, they're not going to say good things about competitors products. I'd like to see an independent study done on the different sensors, before making a decision.

 

[Delps8]

I can't find where they talk about the photobio.

My problem is, it's a paper written by employees of apogee. I mean, they're not going to say good things about competitors products. I'd like to see an independent study done on the different sensors, before making a decision.

It's referenced as the "Hydrofarm" meter.

I understand the hesitancy to trust a paper written by a competitor. In this case, I'm giving the nod to Apogee for a couple of reasons. One is that they're putting it on the web where Mr. Google will find it and that means that HydroFarms attorneys will find it. That's the most defensive posture for Apogee. On the other hand, given that Apogee has the Hydrofarm meter in other documents, I'd argue that indicates that they're pretty certain that their data are correct. Those are assumptions, granted.

Re. saying "good" things - I concur. It's a review of performance of a PAR meter so they can let the data speak for themselves.

"before making a decision" - If I was in the market today, I don't think I'd buy a PAR meter. The Uni-T is close enough and the Bluetooth feature makes it easy to take multiple samples of the canopy. Do the 0.015 conversion and then adjust fire, right?

 

[1212ham]

I've tested Photone twice on my iPhone xsMax. The first time was with a blurple. Photone could not provide a value. The diffuser was in place and I had selected the blurple profile. I tested Photone again last summer with a Growcraft X2 and it was consistently 16% high. The fact that it was consistent is good. The fact that it was that high is not.

RE. the chart for Photone - when I was testing Photone, I contacted growlightmeter.com. I've been writing software for a living since the early 90's (second career), mostly running my own business but I did work for Apple for a few years, so I have some insight into the programming problem.

I contacted them because I cannot find anything in "the research" that indicates that light values should be dropped going into flower. Basic plant bio tells us that dropping light levels will tend to decrease growth. Real world research shows that there's an almost linear relationship between light levels and crop quality and yield. With that in mind, I contacted GLM and they stated that the drop in DLI was due to the change in photoperiod. If that was the case, the DLI would not increase after flip. After receiving that reply, I did not pursue that topic any further.

When I inquired about why they recommend a DLI of 45 for autos, the response was that their understanding is that autoflowers can be treated as always being in veg so they recommend a DLI of 45 through the rest of the grow. I was surprised that they take this approach. Unlike the first point, which is simply completely wrong, this second point is…strange. I cannot understand why a company would be giving recommendations with "our understanding is…". That was disappointing and helped me reach the conclusion to not use their products.

When I asked if they had research to support their recommendations, he told me to check the bottom of the web page for citations.

The first tests I did of Photone were using three weights of paper - 20, 22, and 24 pound because, at that time, they did not have a recommendation. As with their recommendations, I was surprised that they didn't specify because using different paper weights gave readings that were 4% to 24% different. That's significant.

The programmer thanked me for my testing and gave me a few sets of year long license keys for all spectra.

I bought an Apogee.

PhotoBio - I've attached a paper from the Apogee site that compares and contrasts PAR sensors. Interesting reading.

I don't recommend Photone unless you have a known good source. That could be meter calibrated to a known good source or to use third party measurements of a grow light. The latter will tend to be less accurate but will be sufficiently accurate.

I am also hesitant to put a $1000 iPhone into a tent and there are usability issues, as well. One of the drawbacks to having the readout in the same device as the sensor is that it limits usability - I can't get a reading at the back of the tent. In contrast, you can use a wand with the Apogee sensor and, with a Unit-T Bluetooth lux meter, the sensor will send the data to a phone.

In addition to an Apogee I bought a Uni-T and that's the approach I would take if I were in the market for a lux meter/PAR meter. The Apogee is an excellent product but at $600 for the sensor + wand, it's not cheap. In contrast, the Uni-T Bluetooth is $32 here in the US and, when used with the correct conversion factor, is, in practical terms, as accurate as an Apogee.

For those that don't know, the Bluetooth version of the Uni-T pairs with a good free app, PPFD Meter. In addition to displaying lux, PPFD and DLI, it can record measurements and do PAR maps. The new version can convert them to DLI maps. BTW, be sure to reset the light source settings after updating!

PPFD METER - Grow Light Meter

The only grow light meter app you need to set your grow lights correctly. Create PAR Map and Measure PAR / PPFD, DLI, LUX with your iOS or Android phone. Including PPFD meter and DLI conversion for plants.

ppfd.app

 

[Hollatchaboy]

It's referenced as the "Hydrofarm" meter.

I understand the hesitancy to trust a paper written by a competitor. In this case, I'm giving the nod to Apogee for a couple of reasons. One is that they're putting it on the web where Mr. Google will find it and that means that HydroFarms attorneys will find it. That's the most defensive posture for Apogee. On the other hand, given that Apogee has the Hydrofarm meter in other documents, I'd argue that indicates that they're pretty certain that their data are correct. Those are assumptions, granted.

Re. saying "good" things - I concur. It's a review of performance of a PAR meter so they can let the data speak for themselves.

"before making a decision" - If I was in the market today, I don't think I'd buy a PAR meter. The Uni-T is close enough and the Bluetooth feature makes it easy to take multiple samples of the canopy. Do the 0.015 conversion and then adjust fire, right?

Sure I'm not arguing it. I have a photobio meter, and at least it seems to work great for me.

I guess my problem is, I've heard the same arguments over pH meters. "This one's best", or "that one's best", when in reality, most of them work pretty damn good. I prefer bluelab guardian. Mostly because I can leave the probes in the res, and I can get replacement pH probes, but outside of that, I'd use Hanna, apera, or Milwaukee, without a worry.

 

[Delps8]

For those that don't know, the Bluetooth version of the Uni-T pairs with a good free app, PPFD Meter. In addition to displaying lux, PPFD and DLI, it can record measurements and do PAR maps. The new version can convert them to DLI maps. BTW, be sure to reset the light source settings after updating!

PPFD METER - Grow Light Meter

The only grow light meter app you need to set your grow lights correctly. Create PAR Map and Measure PAR / PPFD, DLI, LUX with your iOS or Android phone. Including PPFD meter and DLI conversion for plants.

ppfd.app

Thank you for posting this. If the app does PPFD maps in real time, that's excellent.

I create a table like this in my grow journal (Excel). In this case, I did 19 samples under my Growcraft X3 running at 280 watts. The standard deviation for PPFD is 126 and for DLI is 6. Those are pretty good since it covers the width and breadth to the plant in my tent.



The Apogee has a sample feature where I can take a reading by clicking a button on the display unit but then I have to scroll through the display and type the values into Excel. Or I can create a Note in my iPhone, put on a headset (!), and dictate the readings. Ugh.

It sounds like the Uni-T + PPFD Meter combo would do away with all of that hassle. Heck, if it's an iOS app I can probably run it on my laptop.

That would be a great combo.

Anyone wanna buy an Apogee?

 

[Hollatchaboy]

Thank you for posting this. If the app does PPFD maps in real time, that's excellent.

I create a table like this in my grow journal (Excel). In this case, I did 19 samples under my Growcraft X3 running at 280 watts. The standard deviation for PPFD is 126 and for DLI is 6. Those are pretty good since it covers the width and breadth to the plant in my tent.

View attachment 5342467

The Apogee has a sample feature where I can take a reading by clicking a button on the display unit but then I have to scroll through the display and type the values into Excel. Or I can create a Note in my iPhone, put on a headset (!), and dictate the readings. Ugh.

It sounds like the Uni-T + PPFD Meter combo would do away with all of that hassle. Heck, if it's an iOS app I can probably run it on my laptop.

That would be a great combo.

Anyone wanna buy an Apogee?

Nope, but I think I might try the uni-t. I've had the ppfd app for about 2 years, but I was told it didn't really work. At least not with my phone (galaxy 21), but I liked the app for the dli conversion. If it works with the uni-t, that's the route I'll go.

 

[Delps8]

Sure I'm not arguing it. I have a photobio meter, and at least it seems to work great for me.

I guess my problem is, I've heard the same arguments over pH meters. "This one's best", or "that one's best", when in reality, most of them work pretty damn good. I prefer bluelab guardian. Mostly because I can leave the probes in the res, and I can get replacement pH probes, but outside of that, I'd use Hanna, apera, or Milwaukee, without a worry.

If you're using the PhotoBio, the Apogee paper might give you some insights into the potential weaknesses in the product. IIRC, there were concerns about drift? Dunno.

If you've got an iPhone, check out Clear Sky/Clear Sky Calculator. Apogee publishes it but I don't (recall) seeing anything that would preclude using it for other PAR meters. Big point is to make sure that the sun is overhead when you take a reading. Phone sensors are not designed to read well off-axis (hence the kludgy diffuser that Photone requires on iOS) so an AM or PM reading might give you bad results.

I'm with you 100% on "the best" - when I see that/hear that in a discussion, I consider that a "warning label" that things will soon devolve into people talking past each other.

Bluelab - amen. Money well spent.