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Indoor growing

Enter your grow space once. Every indoor tool knows it.

Tents and hydro run on a handful of numbers growers check daily — VPD, DLI, EC. The calculators here compute them from measurements you can actually take, say how accurate the reading really is, and share one profile: your tent, your light, your reservoir.

6 of 6 tools live. Nothing here requires an account; the profile is stored in this browser only.

Your grow space

The PPM scale matters more than it looks: the same water reads 40% higher on a 700 meter. Saving it here keeps every EC/PPM page on this site consistent with yours.

The indoor toolbox

Hydroponics and grow tents — the numbers growers check daily.

VPD Temperature and humidity → vapor pressure deficit, with stage targets and a printable chart. DLI PPFD × photoperiod → daily light integral, against crop targets. Grow Light Coverage Space and target PPFD → the light output and wattage you actually need. EC ↔ PPM The 500 vs 700 scale, explained and converted. Nutrient Dosing Target EC and reservoir size → milliliters of each part. Reservoir Top-Off Current EC and volume → how much water or nutrient brings it back on target.

Guides

The why behind the numbers.

Grow tent humidity: how big a dehumidifier, really Your exhaust fan moves more water than your dehumidifier does — and the pint number on the box is measured at 65 °F, not tent temperature. Grow light spectrum: what the colors actually do Red wins the efficacy race on physics, not quality — and green beats blue, which is the opposite of what you’ve been told. Reservoir temperature: why warm water kills roots Warm water holds less oxygen while roots demand more of it — and no air pump can beat a falling ceiling. Hydro systems compared: DWC, ebb-and-flow, NFT, Kratky Two buffers decide it: what a power cut costs, and how fast the EC drifts when you’re not looking. Nutrient deficiency ID guide Old growth or new growth halves the list — and the three most-diagnosed deficiencies usually aren’t. pH in hydro: ranges and adjustment The published doses disagree by 4× because they leave out your water’s alkalinity. Here it is computed.

What the profile feeds

Tent size turns a light's output into PPFD over your canopy and a target PPFD into the light you need. Watts and photoperiod give a daily light integral and a power bill. Reservoir volume turns a target EC into milliliters of each nutrient part, and a drifted EC into the amount of water or nutrient that brings it back. The PPM scale is the one that causes arguments: EC is the real measurement, and "PPM" is EC multiplied by whichever constant your meter's maker chose — 500 or 700 — so two meters in the same bucket disagree by 40% while both being right. Save yours and every page here speaks your meter's dialect.

Why the indoor tools live on their own profile

The lawn tools share a yard profile — area, grass, zone — because every one of them scales from square footage. A grow tent has nothing in common with a lawn except the owner, so it gets its own, and neither form asks for the other's numbers. Both live in this browser's storage only; the privacy page shows exactly what's stored and clears it.

What these tools won't do

Tell you a "perfect" number. VPD bands are grower convention, DLI targets are crop research done under conditions that aren't your tent, and every reading you take has an error bar the page will show you. The calculators are for getting into the right range and knowing which lever moves you — not for chasing the second decimal.