Free aquarium tool · updated May 2026

Fishless Cycle Ammonia Dosing Calculator

Free fishless cycle ammonia dosing calculator. Enter tank volume + target ammonia ppm, get the exact mL of pure ammonia (Dr. Tim's, Janitorial Strength, or Ace Hardware) to dose. Cycle in 4-6 weeks.

Reviewed by Fast Aquatics husbandry team·Updated May 2026

Ammonia volume to dose + frequency

Tank volume (gallons)

Target ammonia (ppm)

Ammonia source

How to use this calculator

Fishless cycle protocol:

Day 1Dose ammonia to 2-4 ppm. Add bottled bacteria (Dr. Tim\'s One and Only, Bio-Spira, Stability) per manufacturer instructions.

Days 2-7Test daily. Once ammonia drops below 1 ppm, re-dose to 2 ppm. Watch for nitrite to appear (week 2-3).

Days 14-28Continue dosing ammonia to 2 ppm whenever it drops to 0. Watch nitrite peak then drop. Nitrate accumulates.

Cycle completeWhen dosed ammonia converts to 0 (and nitrite to 0) within 24 hours. Do a 50% water change before adding fish to drop nitrate.

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Browse the full calculator library for tank stocking, water change, dosing, PAR, electricity cost, heater sizing, CO2 BPS, salt mix, and more.

Aquarium-keeping fundamentals

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.

Frequently asked questions

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.