Aquarium Equipment: Filters, Heaters, Lights and Substrate

A freshwater aquarium runs on four pieces of equipment: a filter sized for the tank, a heater for tropical fish and bettas, a light on a timer, and a substrate that suits the fish and plants. Size the filter and heater to the tank’s volume, and buy all four before any fish arrive.

Each chapter in this section takes one piece of hardware and explains how to choose it for your tank size and your fish.

Filters for every tank size

The RSPCA says no fish should be kept without a working filter. Four types do the job in different ways: hang-on-back filters suit most tanks from 10 to 75 gallons, canisters suit big or goldfish tanks, sponge filters give bettas gentle flow, and internal filters fit nano tanks. Aquarium filters compared explains how each works and how to clean the media without losing the bacteria.

Aquarium filters: canister, hang-on-back, sponge and internal

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• Canister filtersBrowse →
• Hang-on-back filtersBrowse →
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Read the tank rating on the box

Makers rate filters by flow in gallons per hour and by the tank sizes they suit. Aqueon rates its QuietFlow canister at 200 gallons per hour for tanks up to 55 gallons, and its smallest internal filter at 0 to 35 gallons per hour for tanks up to 5 gallons. Buy a filter rated for at least your tank’s volume; for goldfish, which make a lot of waste, size up.

Filter care matters as much as the filter. RSPCA Australia says to rinse filter media in tank water, never tap water, and the Marina kit manual says never to change all the cartridges at once. Both keep the bacteria that the tank’s cycle depends on.

Heater wattage and lighting hours

Tropical fish and bettas need a heater; goldfish usually do not. Aqueon’s rule is 5 watts per gallon up to 55 gallons, so a 20 gallon tank takes a 50 to 100 watt heater. University of Illinois vets give bettas 76 to 81°F. Aquarium heaters covers wattage by tank size, running costs and heater safety.

A light is for viewing, for a steady day and night, and for plant growth in planted tanks. An outlet timer is the simplest way to hold the RSPCA’s 8 to 10 hours. Aquarium lighting compares LED lights for plain and planted tanks.

Substrate, rocks and driftwood

Gravel suits most tanks, sand gives a softer look, and aqua soils are for planted tanks. Decor can change the water: Aqueon says driftwood can lower pH through tannins and limestone raises it. Rinse substrate and decor before use and never use soap, as the Marina kit manual warns. Substrate and decor compares each type and the safe choices for long-finned fish.

Equipment chapters at a glance

For the full list of what a new tank needs, start with the setups section.