MV bulbs

[joanna]

I know loads of posts on them but with some, people wouldn't use again, yet others swear by. I don't use any at the mo but I'm looking for a bulb that will provide good uv levels. I don't want one that will be useless after a month. I'm looking for one to go over a table that is 2ft x 3ft. Any ideas as to which I should go for?

[Alan1]

I have only had 3 brands of bulb, solarglo, mega-ray and arcadia.

I bought a solarglo recently with the intention of starting to use it at the same time as my Arcadia just to compare how they fared as regards losing UVB over a period of time.

The UVB output from the new solarglo was only 39 while the arcadia was 182. after about a week the solarglo dropped to only 20. I got a replacement but it was only producing 50 from new and a few weeks later it's no use as regards UVB. From new, bulbs drop a fair bit in the first few weeks and then level off a bit and decrease more gradually. My arcadia was 182 and after 10 weeks or something is 143. it is guaranteed to light for 1 year and they are currently £36 reduced from £60 at surreypets. it is 160w but produces about the same heat as a 120w.

The mega-rays have good levels of UVB too although all MV bulbs can vary. I had one mega-ray that was producing about 150 from new but it blew before too long and another I had was producing 70 from new and only dropped to 54 after 9 months or something so, not great to begin with but didn't decrease a lot in that time.

Frances Baines told me once that 100 uW/cm2 from a bulb (measured at 12 inches) is ideal and 80uW/cm2 is still a decent level

[yuna1971]

I can still get at least 160w/cm2 from my year old MR.
I think TBH, invest in a solarmeter 6.2 Jo, as well (if you possibly can) this will be invaluable as to whether you do get a good one or a dud one. Its all guess work otherwise...unless it just blows that is.

[Alan1]

the problem with all MV bulbs is that none of them guarantee a specific level of UVB. For example Solarglos claim 'optimum levels' of UVB but what does that mean? I don't consider 39uW/cm2 from new as optimum levels. Arcadia claim that theirs are around 180uW/cm2 and in my one that was correct but there are no guarantees either.

Rach that is extremely high for a year old bulb, are you measuring 12" from the top of the solarmeter to the bulb - i.e. 16.25 inches from the substrate to the bulb face?

[yuna1971]

Hmmm...Yeah, see your point. I think I just took it from top of Lilys shell - pointing to the bulb. I mean...wouldnt that be more appropriate, since its the shell and the tortoise we are concerned about?
Scenario is Lily under the light - brightest spot (he happens to be in it now and again). I then hold the SM on the top point of his shell - sensor pointing upwards to the bulb. Then press the button.
If its wrong then so be it, - you arent going to always have him 12inches below so of course its going to be higher than what it would be at say, 15inches. Its weird how when testing its almost like controlled conditions for experiment sake, rather than finding out what the tort actually can get by you measuring from his shell....
Silly point or valid point, Al...??

[yuna1971]

I could just be getting confused...
Memories of when I first got the SM and I was pointing it downwards to the soil...lol (Remember..??)

[yuna1971]

.... I shall go and do a experiment Teacher,...thanks
((skulks away.....))

[Alan1]

It's just for the measuring of the UVB though, you can have a tort under your solarmeter if you like as long as the tip of the meter is 12 inches from the bulb. the only thing that matters is that distance. the solarmeter is 4.25 inches or 110mm if you like so if the meter is on top of the tort then the bulb should be 16.25 inches above the tort so that there is a 12 inch gap from the top of it. after measuring, you then set the bulb back to whatever height you want, that 12" is for a measurement value only and it's only to compare with others' readings that 12" is used as the distance




apologies joanna for a bit of hijacking of the thread

[SeeShell]

So, what do people think is best? I will be getting a new 160W combined shortly, for a large enclosure (6 and a half feet by 3 and a half feet) and am thinking I'll go for the arcadia. Alan / Rach - how much is the Solarmeter 6.2 and can I ask where you got yours?
Thanks
SS

[yuna1971]

I shall take that on board and have another look Al, cheers bud.
BTW, that diagram is well handy for people who wish to know the distance and how to measure... xx