gillcalc

Free, no-login aquarium calculators built on community-verified rules. Every number shows its source and confidence grade.

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• Fish Tank Substrate Calculator — gravel and sand amount by weight, volume and bags, with depth warnings.
• Aquarium Volume Calculator — gallons, liters and true water volume for any tank shape, with footprint and full-weight readings.
• Water Change Calculator — gallons to swap and the nitrate dilution schedule.
• Aquarium Heater Calculator — heater watts by tank size, with dual-heater guidance.
• Aquarium Dosing Calculator — ml, tsp and packets from the manufacturer label.
• Aquarium Light Calculator — lumens and watts ballpark with PAR targets.