Fertilizers and dosing
What dry salts and bottled fertilizers put into the water, in mg/L, and what the main dosing methods prescribe.
Every dosing number on this site comes from the same arithmetic: grams of a salt times the mass fraction of the nutrient in it, divided by the tank volume. The guides below show that arithmetic with real molar masses, then apply it to the two best-known dry-salt methods (Estimative Index and PPS-Pro) exactly as their authors wrote them up.
Product guides stay with what manufacturers declare on labels and data sheets. Where a label leaves a value out, the page says "not published by the manufacturer" instead of filling the gap.
10 guides
- 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.
- Nitrogen, phosphorus and potassium in planted tanksWhat N, P and K do in plants, the forms plants take up, how aquarium dosing expresses them, and what growers and dosing methods say about each.
- PPS-Pro: the lean daily dosing method and its targetsPPS-Pro as its author published it: two 500 mL bottles, 1 mL per 40 L a day, low water-column targets, and how it differs from EI in intent and arithmetic.
- Reading fertilizer labels: P2O5 and K2O to elemental P and KWhy fertilizer labels list phosphorus as P2O5 and potassium as K2O, the exact conversion factors, and worked examples using real aquarium product labels.
- What all-in-one aquarium fertilizers declare on their labelsSeachem Flourish and Tropica Premium and Specialised Nutrition, side by side: declared composition and what one recommended dose adds in mg/L.
- Mixing dry-salt stock solutions: solubility, separation and storageHow to turn dry fertilizer salts into a dosing bottle: solubility limits from PubChem, why phosphate and iron go in separate bottles, and storage and safety.
- Root tabs and nutrient substrates: feeding through the rootsWhat Tropica and Seachem state about root capsules, tabs and nutrient substrates: contents, placement, how long they last, and where their own pages disagree.