claudiusx":16uendem said:
I refer you to revisit your physics textbook and look up the INVERSE SQUARE LAW
, this is highschool science.
In simple terms
It can also be mathematically expressed as:
or
So calculate away , if you assume any given UV-index of under 0.1 is your zero , you can easy work out far you need to be away from the source to get this.
Or simply refer Arcadia's own data for the T5HO tubes as sumarised here :
for a T5ho 12%UVB tube without a reflector , the UV-I at 60cm from the tube is near 1 ,
for a T5ho 12%UVB tube with a reflector hood , the UV-I at 60cm from the tube is about 2.5
, it's not practical to have a tank tall or long enough to get UV-I under 0.5 with a T5ho or a T8 UVB tube.
ie UV-I for T5ho 12%UVB tube in a reflector hood will require
D(0.1) = squareroot ((8.2/0.1) x 30 ^2) = 272 cm
D(0.5) = 121.5cm (48 inches)
D(1.0) = 86cm (34 inches)
The ONLY PRACTICAL way to give the dragon a ZERO UV-I area is to give it a hide.
Can not ignore the physics.
The minimum practical height for a bearded dragon's tank is governed more by the way the basking globe and basking spot are set up than by the UV source to basking spot distance , it's necessary for the basking globe to produce a basking spot at a maximum of 40 degC (AIR TEMPERATURE) this will be determined by the wattage of the basking globe , and try to have the t5ho 12%UVB tube and reflector about 12 inches from the basking spot.
I did some calcs to design my new tanks some time ago and I settled on a minimum height per bay ( lights all mounted from the roof of each bay) of 45cm which gave me a bit of "wriggle room", 80W basking globes , 12%UVB T5ho tubes in reflector hoods , solid timber tops ).
You will have more flexibility if you incorporate a dimming thermostat in the basking globe setup, this way you can simply dial up the air temperature (or surface surface (will be different dependent on the emissivity of the surface being warmed - that's another issue), depending how you set up your thermostat's probe) and let the thermostat respond to the ambient conditions. Then the aim is setting up the uv source to give the level of UVB (or UV-I if you choose to go that way) at the basking spot.
A thermal and a UV gradient are both desireable and your dragon will migrate to and throw throughout the day as it feels the need.