Daily light (DLI)
How much light the plant gets in a whole day. It joins brightness (PPFD) and hours on, so 18 hours of gentle light can beat 12 hours of strong light.
30.2mol/m²/day
EC and PPM converter
Meters show the same water as different PPM numbers depending on their scale. Type in any box and the rest follow.
Which scale is my meter? Most US pens (Hanna, Milwaukee, HM Digital) use 500. Truncheon and many Australian and European meters use 700. Some Eutech meters use 640. If in doubt, EC is the same on every meter.
VPD
How hard the air pulls water through the leaves. Too low and growth stalls and mould creeps in; too high and the plant shuts down to save water.
1.20kPa
Electricity cost per run
What a grow costs to run, from the light's real wattage (the watts it pulls from the wall, not the "equivalent") and your price per kWh from your power bill.
$0
$0
Drying and curing check
Slow and cool keeps the smell and flavour. The usual rule is "60/60": about 60 °F (15–21 °C) and 60% humidity for 7 to 14 days, then jars at 58–62%.