Par Question / Photone App

Hey everyone, I am on my 3rd grow now, I have been successful but my autos have been small so I turned up the light this time earlier and higher intensity than previously, Everything has been going much better with size, the only gripe was an surprising early flower at the end of week 3.

I purchased the Photone app and was shocked to get readings of 750 - 970 par on the canopy… this seems awfully high for week 6 of an auto grow (end of 3rd week of flower) but I see no signs of distress, no curling, bleaching, etc. should I keep this current intensity level? I am afraid to burn my Trichomes or degrade terpenes…

Also if anyone has any experience with the accuracy with the Photone app and it’s accuracy I would appreciate it.


morning @Drewincincy … I use the photone app on my IPhone…you must use a high quality 96 brightness printer paper for the diffuser to get good readings…I use the DLI measurement mode and had to pay $5 to unlock the LED Full spectrum function…I am not on my home computer so I don’t have the DLI chart to share but I suggest using it…have a great smoke session today :cowboy_hat_face:


750 at the canopy is a good reading. Like @Retiredoldguy I use DLI as well. 2 plants week 4 of flower in a 2 x 4 tent :love_you_gesture:

Center of canopy

Far edge of the grow space


Photone can be close but definitely different per phone. Ive compared my light to multiple phones, all were different. Even after calibrating to known par map, still was not even within ten percent of a apogee. After one grow with a certain phone it can be dialed in based on how plants act. I would still compare to known 3rd party testing to have a base line


Iphone needs paper diffuser over phone sensor. Not sure it needs calibrating.
Android doesn’t need diffuser, but needs calibration as all phone brands are different.

I tried calibrating on my Android from light manufactures PPFD map and it didn’t seem right at all, and neither did the stock setting. I ended up buying a $15 LUX meter just to calibrate through the LUX setting in the photone app, then the PPFD and DLI readings seemed more in line with expectations. Although I guess I’ll never know for sure without a real light meter, I was previously using a kill-o-watt meter to set the wattage, so I did have a known baseline for expectations at least.


In your case with a lux reading, if you got a hlg light, you can convert the lux to ppfd on there site. That would be a good way to do it. Problem is to convert from lux to ppfd, you need certain chip characteristics, which the site does automatically.


Good to know about HLG.
I only used the lux meter to calibrate the photone app with though.
I don’t think I’ve even used it since then.


IPhone 11 needs no calibration…when I first got the app I compared my readings to a youtube video on my light using the Apogee meter as the standard and I was within 5% at worse…I have not checked since that time but I can say my girls are much happier since I started using the app and DLI … I have seen several growers with a Android phone express their disappointment…


My android and app maxed out at 35K, outdoors mid summer at high noon.
My UT383BT meter reads 100K lux at same time.
Happy to use android for the BT recording of measurements.

@DEEPDIVERDAVE, is this the Lux meter that you have?
If so how do you like it? I kinda have reservations, as it is $35 and from Amazon.

Yes, same Meter (UT383-BlueTooth) and I do like its usefulness.
The numbers for lux (and conversions) come close to HLG printed specs for my 350R and 260D-Kit.
HLG has calculators for WATTS, LUX, PPF to PPFD or some other inputs (HLG/Resources/Calculators then (?)
Most of all, it confirmed the (my) Android and free App were junk, or I fubar-ed them.
Sometimes, the exponent is difficult to see, if lights are real bright (8/1, outdoors, high noon, sun shining) reads 100 lux (with the exponent +XX in very small visibility, as in above 99,000K lux).
I paid more, like $55.00 last summer.

Equally impressed with the Ladybug dispersal and current activity.
Hope they are effective because until I confirm I won this aphid campaign, the garden is on its own. L-Bugs busy visiting the seedlings, clones, and revegers.

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Thanks, I will get that paper to make sure readings are good