Posted: Sun Mar 23, 2008 11:34 am
Good question. It's advisable to have the bulbs hanging straight down over the basking spot - rather than at an angle - or at least as straight down as you can get it to protect their eyes from the glare. Turtles normally look forward, rather than straight up - like we do - though they do look up from time to time. If the light is making their eyes uncomfortable, they will avoid it, just like we would.
Turtles can tolerate a good deal of glare. Consider how they live in the wild. They tend to bask under the bright sun when it is highest in the sky. They can bask daily for many hours at a time under such light.
One reason we try to be rather specific about the type and strength of the UVB bulbs in a turtle tank is to try to prevent people from inadvertantly gettiing bulbs that are too strong. For a while, at least, there was a popular brand of bulb that was putting out UVB that was not only too strong but was also of an inappropriate wave length and it was seriously irritating turtle (and other basking reptile) eyes. The company that made the bulb is supposed to have taken measures to correct the problem but once in a while, we still hear from somebody who has apparently gotten one of the bad old bulbs and their turtles eyes are swelling and they are refusing to bask and the people don't know what's wrong.
As long as you're using a good, well tested bulb and positioning it correctly your turtle will be fine. All over the world turtles and lizards are basking under good UVB bulbs and thriving. If a bulb is hurting their eyes, their eyes will get irritated and they will refuse to bask. Otherwise, you are good to go.
SpotsMama