Planted Tank Lean Dosing Calculator

Planted Tank Lean Dosing Calculator

Estimate capped weekly nitrate, phosphate, and potassium additions from tank volume, plant mass, light level, CO2 support, current tests, and dose frequency.

🌿Lean Dosing Presets

📐Tank, Plant, and Nutrient Limits

Higher reserve leaves more room for test error and fish food input.
Used only to estimate total liquid mL per dose.

Lean Weekly Dosing Plan

Weekly NO3
--
ppm nitrate
Weekly PO4
--
ppm phosphate
Weekly K
--
ppm potassium
Per Dose
--
--

Dosing Style Comparison Grid

2-5
shrimp-safe NO3 ppm weekly
4-8
low-tech NO3 ppm weekly
6-12
balanced lean CO2 NO3 ppm
10-18
high-light capped NO3 ppm

📊Lean Nutrient Target Ranges

Dosing styleWeekly NO3Weekly PO4Weekly K
Shrimp-safe lean2-5 ppm0.10-0.40 ppm3-8 ppm
Low-tech lean4-8 ppm0.20-0.70 ppm5-12 ppm
Balanced lean CO26-12 ppm0.40-1.00 ppm8-18 ppm
Carpet push lean8-15 ppm0.60-1.40 ppm10-22 ppm
High-tech capped lean10-18 ppm0.80-1.80 ppm12-25 ppm

🧪Dry Salt Nutrient Conversion

SourceMain nutrientNutrient fractionPlanning note
Potassium nitrate KNO3NO3 plus K61.3% NO3, 38.7% KAdds potassium while raising nitrate
Monopotassium phosphate KH2PO4PO4 plus K69.8% PO4, 28.7% KSmall amounts move phosphate quickly
Potassium sulfate K2SO4K only44.9% KUse after KNO3 and KH2PO4 potassium
Trace mix or chelated microsIron and tracesProduct-specificDose separately when macro caps are tight

📅Weekly Schedule Reference

Dose daysBest fitPer-dose sizeWater change cue
2 per weekLow light and slow growthLarger, simple doses20-30% weekly is usually enough
3 per weekMost lean community tanksModerate split doses30% weekly keeps caps predictable
5 per weekHigh light or CO2 tanksSmall frequent doses40-50% helps reset test drift
7 per weekAutomated doser systemsVery small daily doseKeep one maintenance reset day

📏Common Tank Lean Starting Points

Tank sizeDimensionsVolumeTypical lean start
5.5 gallon16 x 8 x 10 in / 41 x 20 x 25 cm21 L2-4 ppm NO3 weekly
10 gallon20 x 10 x 12 in / 51 x 25 x 30 cm38 L3-6 ppm NO3 weekly
20 long30 x 12 x 12 in / 76 x 30 x 30 cm76 L5-10 ppm NO3 weekly
40 breeder36 x 18 x 16 in / 91 x 46 x 41 cm151 L6-12 ppm NO3 weekly
75 gallon48 x 18 x 21 in / 122 x 46 x 53 cm284 L8-15 ppm NO3 weekly
125 gallon72 x 18 x 21 in / 183 x 46 x 53 cm473 L10-18 ppm NO3 weekly
Lean dosing depends on test context. Enter the current nitrate, phosphate, and potassium estimates before using caps, because fish food and aquasoil can already supply part of the week.
Adjust one nutrient at a time. If new leaves pale, pinhole, or stall, raise the limiting target slightly and hold the schedule steady for a full week before changing again.
This calculator estimates lean planted aquarium macro dosing. It is a planning tool, so confirm with reliable test kits, stable CO2, livestock behavior, and repeated plant response before increasing targets.

Nutrient dosing is the mystery recipe for most new aquascapers. They see somebody’s post on a forum thread from 3 years ago that keeps his stem plants green, he copied those milliliter amounts into his tank too. But the other person probably use different light strength, injects a different amount of CO2, and has a different tank size. So their concentration in the water column are different, which is fine for them but turns into an algae issue in your tank.

Lean dosing with a structured approach save money and time. No guesswork here: you’re calculating what plant can eat given its environment. Starving your plants with lean dosing? No such thing. It provide only as much of each element as they require, leaving no leftovers for opportunistic algae.

How to Balance Plant Food for a Healthy Tank

Algae feed on extra nutrients, especially when the balance between nitrate, phosphate, and potassium is off. A simple way to think about it is that potassium is used for structural integrity and water regulation, while nitrates and phosphates must also be kept in balance to avoid algae. So a balanced mix include all three, there’s a formula for this, but computerized calculator does the tricky math after you describe your tank conditions.

You enter the existing levels of nitrates and phosphates because tap water and fish food has some nutrient contribution. If you fail to account for those baseline levels, you will inadvertantly overdose your tank and cause a green water outbreak. This is most frequent cause of an outbreak. What drives that is actual availability of CO2 and light.

You need carbon and energy to use them. Add all the fertilizer you want, if there’s not enough light or injected CO2, nothing happen. That’s why the tool shifts its recommendations based off this interaction.

Because invertebrates like shrimps are sensitive to ammonia fluctuations and nitrate spikes, a safe tank for them will requires ultra-low nitrates (often <5 ppm added weekly). However, a high-tech carpet tank with steady CO2 will be able to take more without triggering algae as long as the ratios stays balanced. This is where reference table on the page makes it clear: the upper limits move up as tech gets higher.

The third macro is typically ignored: potassium. Plants needs it to regulate water and maintain structure. That’s why it runs low when your plants are growing. Most hobbyists pay attention to phosphate and nitrate levels, however they let their potassium levels drop, which results in brown leaf edges and tips or transparent leaves. The calculator monitors potassium separately so you always has enough to help control algae.

And part of that strategy is splitting up dosing. Applying small amounts multiple times a week maintain a constant concentration. This avoids feast-or-famine cycles that stress plants and promote algal blooms.

This also requires using test kits. Don’t depend on what it look like or how you feel. Ignoring background inputs like fish food and tap water can lead to accidental overdosing. What do I mean? How can you tell if you’re on target if you don’t know where you started? That’s why a baseline is necessary, knowing where you are each week before making additions so you know whether you’re within range or all over the place.

Adding more isn’t going to bring down your existing nutrient readings. You’ll just be driving tank further into the danger zone. The goal is to remain in the green, below the caps. Using the tool allow you to calculate how far from your target point you are.

You’re aiming for a peaceful tank, with growing plants doing their thing in an uneventful manner. Make one change at a time, wait for a complete growth cycle, and reassess. More pinholes/pale leaves? Increase this limit factor. Algae shows up? Decrease this target, or add more water changes.

It is an iterative approach that develops your intuition. No formula will ever fully replace it, but knowing good starting points greatly eases the learning curve. Instead of simply reacting to issues, you’re able to prevent them by keeping everything balanced and clean, where each drop matter.

Planted Tank Lean Dosing Calculator

Author

  • Ronan Granger

    Hi, I am Ronan Granger, the owner of AquaJocund.com! At AquaJocund, I’m thrilled to take you on a captivating and immersive journey through the wondrous realm of aquariums and aquatic life.

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