Help and support

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Taking a good reading

Choose the light source on the Meter screen: daylight, white LED or purple grow light.
Stand where the plant is and hold the phone at leaf height, pointing the back camera at the window or lamp.
Hold still until the reading says Steady.

Switch "How to hold it" to Front camera.
Put the phone where the leaves are, screen up, so the front camera looks toward the window or lamp.
Keep your head and hands out of the way and wait until the reading says Steady.

Lay a sheet of plain white printer paper where the leaves are.
Switch "How to hold it" to White paper and aim the back camera at the sheet from about 20 cm (8 in), without casting a shadow on it.

Use whichever is easier for the spot. Calibration is stored separately for each.

PPFD (µmol/m²/s): How much light plants can use is arriving right now. Lux measures light the way human eyes see it; PPFD counts the photons plants use for photosynthesis.
Daily light, DLI (mol/m²/day): PPFD added up over the day. It is the number that best predicts how well a plant grows. Set the hours to your grow light's timer, or to the daylight hours at a window.
How close the estimate is: Usually within about 25% before calibration, more under purple lights, and around 10% once calibrated against a real meter. The thin whisker around the mark on the light scale shows that spread.

Is Leaflux as accurate as a quantum sensor?: No, and it doesn't claim to be. It is good enough to tell a dark corner from a good windowsill, or a lamp that's too high from one that's right. If you own a lux or PPFD meter, use Settings > Calibrate once and readings get much tighter.
Why are purple grow lights so uncertain?: Red and blue LEDs put out lots of plant light but little light that cameras and eyes respond to, and every fixture mixes them differently. Treat the number as a rough guide and compare spots against each other.
My window reading changes all day.: That's real. Save two to four readings to the same spot across the day (morning, midday, afternoon) and Leaflux averages them.
The meter says "Too dark to read".: The camera has run out of sensitivity. Try the other technique, or measure with a little more light; very dark spots are too dark for almost any plant anyway.
How do I restore my purchase on a new iPhone?: Open Settings in Leaflux and tap Restore Purchases, signed in with the same Apple Account you bought it with.
Does it work on iPhone Duo?: Yes. Open it and point the back camera at the light, or lay it flat and use the inner front camera; the layout keeps clear of that camera while it measures. Opened, the reading and the advice sit side by side; folded like a book, nothing sits in the crease.
Can I get a refund?: Refunds for App Store purchases are handled by Apple at reportaproblem.apple.com.