The arithmetic of a planted tank, shown in full
Calculators for fertilizer dosing, CO2 and water chemistry that print their formulas, and plant profiles built from what growers publish rather than from forum averages.
Calculators
Every tool explains its method and links the data it uses.
- Dry fertilizer dosingConvert grams of KNO3, KH2PO4, K2SO4, Epsom salt or a trace mix into mg/L for your tank, or work back from a target ppm. Every molar mass is shown.
- EI and PPS-Pro plannerTurn the Estimative Index and PPS-Pro, as their authors published them, into grams or milliliters for your tank, with the build-up each schedule produces.
- CO2 from KH and pHEstimate dissolved CO2 in mg/L from carbonate hardness and pH, with a temperature-corrected constant, the usual chart shortcut, and the pH needed for a target.
- Water-change dilutionWhat a water change does to nitrate, phosphate, TDS or any dissolved level, the change needed to hit a target, and where weekly dosing settles.
- Stock solutionPlan a bottle of dissolved fertilizer salts: what each milliliter adds to your tank, how long the bottle lasts, and whether the salts will dissolve.
- Hardness converterConvert GH and KH between German degrees, mg/L as CaCO3, mmol/L, meq/L, grains per gallon and French or English degrees, with each definition shown.
- Tank volume and weightNet water volume and weight for rectangular, cylindrical, bow-front, corner and hexagonal aquariums, minus glass, the gap below the rim and the substrate.
- Substrate volumeHow many liters of aqua soil, sand or gravel a tank needs for a flat bed or a front-to-back slope, and how many bags that is.
Plants
Grower ratings for light, CO2, growth and difficulty, accepted names and native ranges from the World Checklist of Vascular Plants, and official noxious-weed listings where they exist.
- Marimo (Aegagropila linnaei): grower data and the zebra mussel findother, foreground / midgroundLight: LowCO2: LowEasy
- Alternanthera reineckii 'Pink': grower data and red colorstemLight: MediumCO2: MediumMedium
- Anubias barteri var. nana: grower data, planting and namesrhizome, epiphyte / foreground / midgroundLight: LowCO2: LowEasy
- Bacopa caroliniana: grower data, color cues and rangestem, backgroundLight: LowCO2: LowEasy
- Bolbitis heudelotii (African water fern): grower datarhizomeLight: MediumCO2: MediumMedium
- Bucephalandra pygmaea 'Bukit Kelam': grower data and namesrhizomeLight: LowCO2: LowEasy
All 27 plant profiles. Compare the grower ratings side by side in the sortable parameter table.
Fertilizers and dosing
What dry salts and bottled fertilizers put into the water, in mg/L, and what the main dosing methods prescribe.
- Calcium, magnesium and GH for aquarium plantsWhat GH measures, how much calcium and magnesium one degree represents, how Epsom salt and GH boosters change it, and the targets EI, PPS and Aquasabi give.
- Estimative Index (EI) dosing: what the method prescribesEI as Tom Barr wrote it up: dose a surplus three times a week, change 50 % of the water weekly, and why that caps build-up at twice the weekly dose.
- How ppm from dry fertilizer salts is calculatedThe molar-mass arithmetic behind every dosing chart: grams of salt to mg/L of nitrate, phosphate or potassium, with worked examples and the common traps.
- Iron and trace elements: what chelates do and how to dose themWhy aquarium iron comes chelated, what EDTA, DTPA and EDDHA products declare, how iron deficiency looks, and the iron levels dosing methods aim for.
CO2 and light
How dissolved CO2 is estimated, measured and supplied, and what light figures such as PAR, PPFD and grower ratings mean.
- CO2 from KH and pH: the formula, the chart and where it breaksWhere the KH/pH/CO2 chart comes from, why its factor of 3 differs from the temperature-corrected 3.5, and the conditions under which both estimates fail.
- How a drop checker works, and what its green actually meansA drop checker is a small KH/pH test with its own reference water. The indicator chemistry, what green corresponds to in mg/L at 4 dKH, and its limits.
- How much CO2 is in aquarium water without injection?Henry's law and today's atmospheric CO2 put water in equilibrium with air at about 0.6–0.7 mg/L. The calculation, the temperature effect and what it means.
- Liquid carbon products: what the labels claim and what is establishedWhat Seachem Flourish Excel and Tropica Carbon Nutrition say about themselves, what their pages leave out, and the hazard data PubChem lists for glutaraldehyde.
Algae and plant problems
Deficiency symptoms, the common algae groups, melting plants and invasive-species rules, with the evidence behind each claim.
- Black beard algae: the red algae behind it and what sources adviseBlack beard (brush) algae are red algae despite their color. The likely genera, the alcohol test, conditions linked to it, and the control methods sources describe.
- Crypt melt: why new Cryptocoryne lose their leavesNew Cryptocoryne often drop their leaves within weeks of planting. What growers and the research on emersed and submerged leaves say, and how long regrowth takes.
- Cyanobacteria (blue-green algae) in a planted tank: causes and controlBlue-green slime is a bacterium, not an alga. What growers and the EPA say about it, the nitrate and phosphate link, and how blackouts and potassium spikes compare.
- Diatoms (brown algae) in a new planted tank: why they come and goThe brown film in a new tank is diatoms, algae with glass cell walls. Why they appear in the first weeks, what silica has to do with it, and what clears them.
How the pages are made
Every non-obvious claim links to a primary source: grower and manufacturer pages, PubChem and IUPAC data, the World Checklist of Vascular Plants, peer-reviewed papers and government or university pages. A value a source does not publish is shown as "not published by the source". Drafting is AI-assisted and each page shows whether the editor has reviewed it.Read the method.