Monthly aquarium operating cost depends on size + type + light intensity. 20-gallon freshwater: $8-15/month. Heater + filter + 1 LED + food + water-change dechlorinator. 55-gallon freshwater: $15-30/month. Larger heater + canister filter + medium-output LED + food + supplements + monthly water test reagents. 75-gallon reef: $40-90/month. Two MP10/MP40 powerheads + return + ATO + 2 reef LEDs + protein skimmer = ~$30-50 electricity alone. Salt mix $15-25, RO/DI consumables $5, calcium/alk/mag dosing $10-25, fish/coral food $15. Drivers of cost: electricity rate (CA = $0.30/kWh vs TX = $0.13/kWh), light intensity (high-PAR reefs draw 200-400W), heater duty cycle (cold rooms = constant heater run). Cost-saving tips: LED over T5 or metal halide, wave makers over high-flow returns, lid your tank to cut heater runtime, run RO/DI from house water instead of buying jugs. Use our aquarium electricity calculator for your exact rate.
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