Estimative Index is the dominant high-tech planted-tank dosing protocol. Concept (Tom Barr): dose enough nutrients that no macro or micro is ever the limiting factor for plant growth. Skip testing - just dose to known excess + water-change away the buildup. Standard EI weekly schedule: 3x weekly KNO3 (nitrate), 3x weekly KH2PO4 (phosphate), 3x weekly K2SO4 (potassium), 3x weekly traces (CSM+B or Plantex). Macros (per 60 gal): 1/4 tsp KNO3 = 7.5 ppm NO3 boost. 1/16 tsp KH2PO4 = 1.3 ppm PO4. 1/8 tsp K2SO4 = 7.5 ppm K. Reset: 50% water change each Sunday clears accumulation. Benefits: rapid plant growth, no deficiency diagnostic, predictable pattern. Drawbacks: heavy water changes, ongoing fert dosing, requires CO2 + high light for plants to keep up. Alternatives: PPS-Pro (lean dosing), ADA (substrate-driven low-EI), low-tech (no ferts at all - low-light only).
Reviewed by the Fast Aquatics husbandry team · Updated May 2026
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Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.
Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.
Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.
Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.
Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.
How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.
What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.
How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.
Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.
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