At Arcadia Reptile, we welcome any proven update to keeping science and practice where it is proven to be safe, impactful, and wild-like. Historically, as keepers, we have always used temperature as our guide for providing heat within our enclosures. We must also factor in the spectrum of a lamp, be this for UV, Infra-red (Heat), or visible light, with the best light sources being as close to the spectrum of the sun as possible.

Temperature has served us well and, of course, is a metric that will always be used. However, this as a scale of measurement only looks at the actual measured temperature of the air or at the probe of a thermostat or thermometer, not the bioenergetic value of that energy.

The sun is the ultimate provider, and its projection onto the earth is the primary source of energy that all life has developed toward. It is its spectrum, balance, and quantity of energy that sustains life. The sun provides around 400-500 W of energy within the Infra-Red range, depending on angle, elevation, and intensity. Therefore, it is not just temperature that matters to life, especially reptiles, it is the bioenergetics of life that really matter: how much energy is present at the skin, and how bioavailable is it. Indeed, it is this fundamental principle of energy transfer that sustains all life.

Thankfully, incandescent lamps such as the SolarBasking and the Arcadia Reptile Halogen range of heating lamps have a very natural, or ‘sun-like,’ spectrum. It is because of this, that we can be confident in their bioavailability to life.

Historically, we as keepers have chosen lamps that will lift an enclosure’s basking spot temperature to the desired level as quickly as possible, then regulated the temperature through dimming. It is thought that a high degree of dimming could shift the lamp’s spectrum away from true infra-red, lowering the bioavailability of the energy being produced. Moreover, we now believe it is better to use a lower wattage of lamp with a wide enough spread of light to cover the whole animal when basking, while ensuring proper ‘power density.’

Power density is a unit of measure that quantifies how many watts of energy are present within a light source. A simple handheld meter can now be used to measure this easily, the same type of meter that solar panel installers use to position panels correctly. In much the same way we measure and read UV Index via a handheld meter and then relate readings from the sun to those of a lamp, we can now also do this with heat sources.

Roman Muryn has been working on this concept for many years, and a good guide to power density and its use in reptile keeping can found through his publications. In short, you will now start to find power density output graphs on Arcadia Reptile heating lamps. In this way, you can be sure that the lamp that you have chosen is delivering the correct level of energy your species requires to thrive, while still using your all-important thermostat to protect your system from any dangerous overheating.

As an example, the Arcadia Reptile Mini Halogen Heat lamp is a small heating lamp with a lens that creates a usable flood. The lamp draws 20 W and therefore, when running at full power, will provide 20 W of heat in total within with cage. However, this lamp will provide around 300 W, as measured by the meter at approximately 18 cm from the lamp. In this case, the lamp will not significantly raise the air temperature, nor quickly, but is does provide enough energy within light in an energy-efficient way for many of the smaller species we keep, including small reptiles, amphibians, and invertebrates.

Our graphs show power density in much the same way as UV Index, with power regions denoted by alphabetic rings of power at distances from the lamp and through colour. All you then need to do is site the lamp with the correct wattage and spread at the correct distance from your animal, grouping all light sources together to create one basking zone with all light sources working together. This is by far the best way to replicate sunlight.