Advanced options
What The Aquarium Heater Cost Calculator Works Out
- Per year: heater watts x duty cycle x 24 hours x 365 days, divided by 1,000 for kilowatt-hours, multiplied by the unit rate. A 100W heater at 35% duty uses about 300 kWh a year, roughly GBP 80 at the current Ofgem price cap unit rate (the default in the electricity field).
- Per month: the yearly figure divided by 12. Real bills are seasonal: the heater works hardest in January, when the gap between room and tank temperature is widest.
- Room warmth (duty cycle): the share of the time the thermostat actually has the element on. A tropical tank at 24C to 26C in a warm living room cycles around 25%; a typical heated home 35%; a cool room, conservatory or a house heated less than it used to be, 50% or more.
- Heater rating: the 1W-per-litre rule sizes heaters for heated homes, so the label wattage is a proxy for tank size. The cheapest watt in fishkeeping is the one the room never stole.
- Custom heater wattage (advanced): pick "Custom wattage" in the heater dropdown and enter the real rating, including the combined figure for two half-sized heaters, which the folklore favours over one because a stuck-on heater cooks a tank and a stuck-off one chills it.
- Duty cycle cut from insulation (advanced): polystyrene on the back and sides, a fitted lid against evaporation and siting away from external walls typically trim 10% to 30% off the heater's running time. The saving card shows what that is worth per year, which usually repays the foam within months.
- Number of heated tanks (advanced): multiplies the heater and equipment figures for a fish room or a house with several tanks.
- Filter, pump and lighting (advanced): the other constant loads. A filter and air pump of around 10W run 24 hours a day; LED lighting of 20W to 40W runs a scheduled 8 to 10 hours. Together they add 100 to 200 kWh a year, and the whole-tank cards show the heater's share of the total, usually 60% to 75%.
- Whole tank per year and per month (advanced): heater plus equipment, the figure to compare against the GBP 60 to GBP 120 a 100L tropical setup typically costs all-in. Coldwater species such as goldfish and white cloud minnows delete the heater line entirely.