Equipment Review and Discussion :: Powersun mercury vapour light

[reptilegrrl]

You're right, Marisa, I totally forgot about that!

The good thing about these lights is that they can be farther away; I hung them about 2 feet above my turtles. But still, having them on all day could be bad, and eye damage could be a part of that. Poor critters.

A local guy has a box turtle that is blind; it was blind when he got it. I wonder if too-close lights could have been the cause?

[marisa]

I think we cross-posted (I went back and responded to some of your earlier comments).

I don't know why the boxie is blind, but somehow doubt the lighting was the cause (what's the set-up like for him?).

The strength of the UVB light drastically diminishes with distance, and unless you're using a really high wattage, two feet sounds like it might be a little far away from your turts. When I first used a 100-watt T-Rex Active UV Heat bulb in a 50-gallon set-up, it was 14 inches from the basking area (my RES wouldn't bask if it was closer, if it had been the temp would have been in the low 90's and he likes the temp at about 88F). The mfgr. recommends that the distance for the bulb be 12 inches, however. Also, since the strength of the UVB light diminishes over time with use, after about 6 months I'm wondering how much UVB a turtle would receive over a 4-hour span and two feet away...

I've never had a problem with the light being on for 11-12 hours a day. I don't recall in the T-Rex literature that 10 hours a day was dangerous, but I'll recheck.

[reptilegrrl]

I think we cross-posted (I went back and responded to some of your earlier comments).

I don't know why the boxie is blind, but somehow doubt the lighting was the cause (what's the set-up like for him?)..

He was blind when the guy got him, and no one knows his history. I am not sure under what conditions he was acquired. He does not appear to have any eye injury, but his eyes are a little discolored. Cataracts can be caused or aggravated by too-bright light.

The strength of the UVB light drastically diminishes with distance, and unless you're using a really high wattage, two feet sounds like it might be a little far away from your turts. When I first used a 100-watt T-Rex Active UV Heat bulb in a 50-gallon set-up, it was 14 inches from the basking area (my RES wouldn't bask if it was closer, if it had been the temp would have been in the low 90's and he likes the temp at about 88F). The mfgr. recommends that the distance for the bulb be 12 inches, however. Also, since the strength of the UVB light diminishes over time with use, after about 6 months I'm wondering how much UVB a turtle would receive over a 4-hour span and two feet away...

The box said it could be placed up to five feet away. I elected not to go for five feet because I didn't want UV all over my living room, and I didn't want to look directly at the light.

I think 12 inches is too close, personally. The flourescents needed to be about that close for the pets to get ANY UV, but having a light that close can't be a pleasant way to live.

My box turtles did very well with theirs about 2 feet away. I saw a marked improvement in their behavior and appetite, compared to the years before, when they had flourescent lighting. That was what sold me on the merc vapor lamps. WHen I firtst bought one, they were new and people really weren't sure if they were better than the flourescent lights. Even one of the vets who was working for them, doing endorsements, told me personally that there was no way to know yet if they were really better. I decided to take an experiment and buy it, and it made such a difference that I was sold. It's funny, my vet, who originally was not in favor of them because they had such a short track record, really didn't want me to get one back then; now he is all in favor of them

[marisa]

I take what the mfgr recommends and adjust according to the temp. The light is never closer than the recommended distance, and is most often further away. (Like I said, Tilly likes high 80's and at 12 inches away the bulb was too warm.)

That's usually the way with "new" products--until they have a track record, people often poo-poo them, sometimes with good cause, sometimes not.

As for the 12 inches, this is generally the maximum distance given for conventional UVB lights that give off lesser amounts of UVB (3%, perhaps 5%)---beyond that the rays are considered to be too weak to really provide that much benefit. I still use one that is supposed to produce 3% UVB and have it about 6-8 inches away from the turtle when s/he basks. I can't say I've seen any problems with it being this close.