FAQ: Heating & Lighting for reptiles

Unlike UVB lamps, basking bulbs are only replaced when they burn out, as their heat output hardly drops over time. Keeping a spare bulb is worthwhile so the terrarium is not left without heat for long, especially in winter.

Ceramic heat emitters usually last longer than basking bulbs, as they have no fragile glass or filament. They can still fail, though, so the temperature should be checked regularly with a thermometer.

It is worth glancing at the temperature daily, for example when feeding or cleaning, and checking the basking surface temperature every few days. Thermometers that record the maximum and minimum help catch night-time swings.

Many lizards, especially bearded dragons, open their mouths briefly while basking to regulate their temperature, and this is usually normal. If the mouth stays open for long, the reptile avoids the lamp or seems to struggle to breathe, check the temperature and see a vet.

When travelling, a reptile is usually carried in an insulated box kept warm by room temperature, and in cold weather by a cloth-wrapped heat pack. Using lamps or mats without a thermostat during travel is not recommended, as they can overheat a small space.

Heat packs can help in cold weather, but they must not touch the reptile directly and should be wrapped in cloth. The box must leave room for the animal to move away from the heat, and the pack must not use up the air.

Ordinary UVB tubes produce almost no heat, so most species also need a separate basking lamp. The exception is mercury vapour lamps, which give both heat and UVB, but they must be matched to the terrarium size.

The UV index shows how strong the UVB reaching a given spot is and is measured with a dedicated meter. Different species receive different UVI in the wild, so the lamp and its height can be chosen so the UVI at the basking spot matches the species’ needs.

UVB zones are areas of the terrarium with different UVB strength: strongest under the lamp and fading with distance to full shade. Such zones let the reptile choose how much UVB to get, much as it moves between sun and shade in the wild.

A reptile does not need to be made to sit under a UVB lamp; it chooses for itself when and how long to bask. What matters is that the lamp runs all day and the terrarium has both sunny and shaded spots.

Fluorescent and mercury vapour UVB lamps contain mercury, so they must not go in household waste. Take used lamps to an electrical waste or lamp collection point, and gather the pieces of a broken lamp carefully and air the room.

Yes, a layer of dust or limescale on the lamp and its guard reduces the amount of UVB that gets through. Now and then wipe the lamp, switched off and cooled, with a dry or slightly damp cloth.

Yes, especially in wooden or PVC terrariums lamps are often mounted inside on the ceiling, so no mesh reduces the UVB. In that case lamps must be fitted with protective guards so the reptile cannot reach them and get burned.

Yes, it is worth setting up and running the terrarium with all its heating and lighting for at least a few days before bringing the animal home. That gives you time to adjust the thermostats, check temperatures on both sides and avoid stress for the new reptile.

Most species need a basking lamp in a ceramic socket, a UVB lamp with a fixture, a thermostat, at least two thermometers and a timer. A ceramic heater or mat may be needed for night heating, and a hygrometer to monitor humidity.

Used fixtures, thermostats or thermometers can be bought if they work and are undamaged, but used UVB lamps are often already worn out. Before using them, check the cables, sockets and thermostat accuracy.

Common mistakes include heaters without a thermostat, one temperature throughout the terrarium, stick-on thermometers, UVB lamps not replaced in time and coloured night bulbs. Most can be avoided by measuring temperature at the reptile’s level and following the species’ needs.

A smart plug can act as a timer for lighting, but most do not control a heater by temperature. Heaters still need a thermostat with a probe, while smart devices can be an extra way to monitor temperature remotely.

Such a sensor can warn you if the terrarium gets too hot or too cold, for example when a thermostat fails or the power goes out while you are away. It does not replace a thermostat, but it adds safety, especially in hot or cold seasons.

An ordinary dimmer can dim an incandescent basking bulb, but it does not respond to temperature, so the terrarium will warm and cool with the room during the day. A dimming thermostat that adjusts power by a probe is more reliable.