If you want to see how a screen top changes a UV Index reading, take a pair of readings at the same marked point, with and without the screen, before the animal is in the enclosure. Keep the lamp and fixture fixed, hold the sensor at the same height and angle, and follow the lamp maker’s warm-up guidance. Repeat the pair a couple of times so one shifted reading doesn’t drive the comparison.
A useful log is: lamp model and age | fixture | mesh type | distance from lamp to sensor | sensor position and angle | meter model | UVI with mesh | UVI without mesh. If you’re tracking a lamp over time, use that same setup at each check. Write down the unit too: a UVB irradiance reading in µW/cm² and a UV Index reading aren’t interchangeable.
Disclosure: I’m affiliated with UVB Meter.
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UVB Meter | UVB vs. UVI guide
