Aquarium Plant Fertilizer app icon

Aquarium Plant Fertilizer

The honest aquarium fertilizer calculator for planted tanks.

Dose dry fertilizers or bottled liquids with confidence. EI dosing, PPS-Pro, custom ppm targets, and label doses for 8 commercial fertilizers — in grams, teaspoons, or stock solutions — with every constant linked to its published source in the Sources section below.

Download on theApp Store Try the free calculator
Free calculator $4.99 one-time Pro Dosing reminders No subscription

Try the free aquarium fertilizer calculator

The same dosing math as the app — EI, EI Daily, PPS-Pro, PMDD, and custom ppm targets — right here in your browser. Free forever, no account; your inputs stay in your browser and aren't sent to Wuffworks.

Teaspoon weights are approximate — powders pack differently. The app lets you weigh your own spoon once and calibrate. Method sources: Rotala Butterfly's nutrient calculator, the UKAPS EI dry-salts guide, Tom Barr's Estimative Index (barrreport.com), the PPS-Pro standard formula, the PO4-modified PMDD recipe (theplantedtank.co.uk), IUPAC atomic weights.

Save this tank on your iPhone

The web calculator is free forever. The iOS app runs the same math, and adds saved tanks plus dosing reminders — $4.99 once, no subscription.

Dosing math, without the guesswork

We kept seeing planted-tank hobbyists piecing together dosing math from forum threads, web tools, and spreadsheets — so we built the simple calculator we thought should exist.

EI, PPS-Pro, PMDD, and custom targets — in one app

Dry powder, mixed bottles, custom ppm targets, and 8 bottled liquids — EI, PPS-Pro, and your own targets live side by side. Compare methods on the same tank instead of juggling three different calculators.

Never miss a dose

Dosing reminders (Pro): a Today card, a gentle nudge each dosing day, and one-tap check-off. Missed yesterday? Dose now or skip — EI and PPS-Pro are forgiving.

Built for the fish room

Native iOS, fully offline. Mix your stock solutions at the tank with wet hands — no signal required, no login, no loading spinner.

Shows its work

Every constant links to its published source — see Sources below — so you can verify the assumptions behind the math. Cross-check any dose against any other calculator.

Honest pricing

The calculator is free. Pro is a $4.99 one-time unlock for unlimited saved tanks and dosing reminders. No subscription, no ads, no data harvesting.

Four ways to dose, one calculator

The ways planted-tank hobbyists actually dose — computed from the published recipes and manufacturer labels. EI, EI Daily, PPS-Pro, PMDD, and custom targets all scale to your exact tank volume.

Method 01

EI Dosing Calculator

The classic Estimative Index method from Tom Barr: dose macros and micros in slight excess, reset weekly with a 50% water change. Get the full EI schedule — dry or stock solution — for your tank size.

Method 02

PPS-Pro Dosing Calculator

The lean Perpetual Preservation System: small daily doses for steady, controlled growth. Standard PPS-Pro recipe in milliliters per day, with per-nutrient ppm breakdown.

Method 03

Custom Target Dosing

Define your own ppm targets and the app works backwards to exact grams — for KNO3, KH2PO4, K2SO4, MgSO4, CSM+B, chelated iron, and GH booster.

Method 04

Bottled Fertilizer Doses

Using Seachem Flourish, NilocG Thrive, APT, Tropica, or Easy-Life? Get the manufacturer label dose for your tank size. We show the label dose only — never guessed ppm.

How it works

Three steps, thirty seconds, dosing day after dosing day.

1

Tell it your tank

Enter your tank size in gallons or liters. Save it once — the app remembers.

2

Pick a method

EI, PPS-Pro, or your own custom targets. Dry salts, stock solutions, or target ppm.

3

Get your dose

Exact grams and teaspoons, plus the nutrient contribution — NO₃, PO₄, K, Mg, Fe.

Take a look inside

Four tabs. Everything within thumb's reach at the tank.

AquaDose Calculate tab screenshot

Dose in grams, teaspoons, or stock solutions

Enter your tank size, pick EI, PPS-Pro, or your own custom targets. The app returns exact doses — plus the nutrient contribution of each one: NO₃, PO₄, K, Mg, Fe.

AquaDose Methods tab screenshot

Every method shows its source

The published recipe behind EI and PPS-Pro, the constants used, and where each number comes from — so you can cross-check any dose against any other calculator.

AquaDose Reference tab screenshot

Every number traces back to a source

Tap any compound to see what it contains and where the data comes from — then calibrate your own teaspoon so every dose uses your number, not an average.

AquaDose Reminders tab screenshot

Never miss a dosing day

Pro reminders: a Today card, a gentle nudge each dosing day, one-tap check-off. Your dose log lives on your phone — no account, no server.

Honest data, or nothing

We don't ask for your trust. We show our work.

Sources

Every number on this page comes from one of these published sources. Check our math.

Simple, honest pricing

The calculator is free. Pro is for multi-tank hobbyists. Never a subscription. ($4.99 in the U.S. — local App Store pricing applies elsewhere.)

Free

$0
forever
  • Full fertilizer calculator
  • Dry dose, stock solution, target ppm
  • EI, PPS-Pro & custom targets
  • 8 bottled liquid fertilizers
  • All compounds, sourced data
  • 1 saved tank · works offline
ONE-TIME

Pro

$4.99
one-time unlock · yours forever
  • Everything in Free
  • Unlimited saved tanks
  • Dosing reminders
  • One-time purchase — yours forever
  • No subscription, ever

Questions, answered

Straight answers about EI, EI Daily, PPS-Pro, PMDD, and dosing dry fertilizers.

Which aquarium fertilizer calculator should I use?

Use one that shows its work. Aquarium Plant Fertilizer computes EI, EI Daily, PPS-Pro and PMDD dosing, custom ppm targets, and bottled-liquid label doses from published recipes and manufacturer data — every number links to its published source in the Sources section below, so you can cross-check any dose against any other calculator. The web calculator is free; the iOS app adds saved tanks and dosing reminders.

What is the EI dosing method?

EI (Estimative Index), published by Tom Barr, doses macronutrients and micronutrients in slight excess so plants never run short, then resets the water column with a 50% weekly water change. The app computes the full EI schedule — macros and micros, dry or as stock solutions — scaling published per-dose targets to your exact tank volume.

What is PPS-Pro?

PPS-Pro (Perpetual Preservation System Pro) is a lean daily-dosing method: small measured doses of macro and micro solutions every day for steady, controlled growth. The app gives the standard PPS-Pro recipe in milliliters per day with a per-nutrient ppm breakdown.

Should I use EI or PPS-Pro for my planted tank?

EI suits high-light, CO2-injected tanks where you want maximum growth and don't mind weekly 50% water changes. PPS-Pro suits aquarists who prefer leaner daily dosing and steadier parameters; PMDD is the classic lean daily method. The app supports EI, EI Daily, PPS-Pro and PMDD, plus fully custom ppm targets, so you can compare.

How much dry fertilizer should I dose per gallon?

It depends on your dosing method, tank volume, and which salts you use. The app works it out from the published recipes — enter your tank size, pick EI, PPS-Pro, or your own targets, and get exact grams and teaspoons for KNO3, KH2PO4, K2SO4, MgSO4, CSM+B, and chelated iron.

How much liquid fertilizer should I dose? (Seachem Flourish, APT, Tropica…)

Follow the manufacturer label — and let the app do the tank-size math. Aquarium Plant Fertilizer includes label doses for 8 commercial liquids (Seachem Flourish, NilocG Thrive, APT Complete, APT Zero, APT EI, Tropica Specialised and Premium Nutrition, Easy-Life Profito), scaled to your exact tank volume. We never estimate ppm from label percentages, because that would need the bottle's density, which brands don't publish.

How do I remember to dose my aquarium?

The app's Pro dosing reminders send a gentle nudge each dosing day, with a Today card and one-tap check-off. Missed a day? Dose now or skip — EI and PPS-Pro are both forgiving.

Can I trust these numbers?

Don't take them on faith — that's the point. Every constant in the app links to its published source — Tom Barr's EI method, Rotala Butterfly's per-dose targets, the PPS-Pro standard formula, the PMDD recipe, and the teaspoon-weight threads we used — listed in the Sources section below, so you can cross-check any dose against any other calculator.

Is the calculator free?

Yes. The full fertilizer calculator is free, including one saved tank. Pro is a $4.99 one-time unlock for unlimited saved tanks and dosing reminders. No subscription, no ads.

Does it work offline? Is my data private?

Yes. Everything is computed on-device and works fully offline — at the tank, in the fish room, anywhere. There are no accounts and no servers; your tanks and mixes are stored on your device and never sent to Wuffworks.

Which fertilizers are supported?

Potassium nitrate (KNO3), mono potassium phosphate (KH2PO4), potassium sulfate (K2SO4), Epsom salt (MgSO4), Plantex CSM+B, chelated iron (DTPA), and GH booster — for dry dosing, stock solutions, and target-ppm calculations — plus label doses for 8 bottled liquids (Seachem Flourish, NilocG Thrive, APT Complete/Zero/EI, Tropica Specialised/Premium, Easy-Life Profito).