Free PAR meter (Apple phones only)

Finally!! Hey guys I wanted to pass along this app only tho if you have Apple its a free ppfd meter accurate too its called korona


Seems like it has paid monthly membership… ‎Korona - Grow Light Meter on the App Store

I’m pretty sceptical about phone camera’s ability to act like professional measuring device in PAR spectrum.

And for some reason they claim to have a “white paper” that proves their accuracy, but they don’t provide it publicly :frowning: … instead they are using it to gather email addresses to mailchimp database :confused: .


It has a lot of shitty reviews I just read some of them

I think you have to pay to play as well,


Just another not-so-clever concoction to take advantage of all the “new” personal growers. Coming soon, an APP to “guarantee bulk/weight”. I’ll pass, TYVM. SS/BW…mister :honeybee: :100: :pray: :heart_eyes:


even if its bunk the idea is now out there, never know

Apogee instruments Bluetooth

Split it amongst a few friends.

Pays for itself


Its free I downloaded it didnt pay a cent and I matched it up with my lux meter and the ppfd chart with my light and it was spot on so do t hate until you try it

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Thanks for the review. Have you checked the difference between paid and free version?

BTW. I’ve signed up for the white paper and they have registered me into mail chimp marketing software but haven’t delivered the paper :frowning:

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If you ever get the paper, could you forward it to me? Thanks.

OP, PFD and PPFD have a specific connotation and generally have special optics and spectral bandwidths associated for measurement. It’s likely a LUX meter with some digital filtering but that doesn’t account for incident angles and such. Details will give us a better sense which are currently missing. Most likely the tool could provide a decent estimate but for specific lighting scenarios.

Personally, I’d prefer free but there is a reason some of the scientific sensors are a bit pricey in comparison. Depends on the precision and accuracy desired and also the type of light source one is evaluating. And then the parameters needed as a response.

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They have something like this for Android as well, Free Lux Meter I believe it’s called. I installed it on 2 different phones and bought a meter from Amazon. Got 3 totally different readings on all 3 devices. I pretty much gave up and decided to learn to read how the plants react to the light instead of worrying about the light value.

That’s a good idea the plants will always tell you