UVB meter arrives today

[Guggie]

Hi all. Question about my new UV meter (the 6.2) that should be at my home today when I get home. I will use it to measure my Greeks' ZooMed 100w MVB that I've had for about 9 months, but what #s am I looking for? How do I know if it's time to replace a bulb that I already have?

Thanks!

 

[TylerStewart]

Hi all. Question about my new UV meter (the 6.2) that should be at my home today when I get home. I will use it to measure my Greeks' ZooMed 100w MVB that I've had for about 9 months, but what #s am I looking for? How do I know if it's time to replace a bulb that I already have?

Thanks!

Be careful not to drop it! I had one less than 24 hours and it fell 3 feet off a table and shattered LOL.... That was painful!

I have the ZooMed UVB meter (reads in microwatts per square centimeter). The readings you get, though are going to be really variable depending on how far you are from the bulb. Moving just an inch or two closer or farther will change the reading quite a bit. I was surprised at how well my old Reptisun bulbs were still working. In most cases, lowering them a few inches made them put out the same UVB to the substrate height than they did when they were brand new (bulbs 12-24 months old). For me, my Powersun bulbs at about 12" distance were putting out the same UVB that I get outside here in 100% shade (backside of my house, for example, was at (40-60 microwatts per square centimeter from the bulbs and in the full shade). Direct sun I am getting about 6 times the UVB from the sun (275-310 microwatts per square centimeter) than my Powersun bulbs put out at 12". In all cases, even on my oldest bulbs, they were still getting some UVB to the substrate. The glass windows on my house don't let any UVB through at all. It's fun to play with, if nothing else. I don't use it a whole lot after checking all my bulbs just to see where I was at.

 

[Guggie]

Lol - that would suck! That's like me getting in a fender bender 2 days after getting my first brand new car. (Bad memories...)

Your meter is the same as the one I'm getting (but rebranded for ZooMed.) I guess I still don't understand what the numbers will mean. My vet told me to use it to measure a new bulb and then measure the % lost over time, and when the bulb was outputting 30% less UVB than it started, replace it. (I think it was 30% - have to look at home.) Is that a good way of doing it? It means I will get rid of my old bulb tonight, which bugs me since it may have some life in it. What I wish I had is a number that said "As long as you're higher than this, your torts are getting enough UVB."

Thanks for your help, Tyler!

 

[MORTYtheTORTY]

good post! Can I bring mine into a petshop or places that can check it for me? If not then where and how much did you pay for your UVB meter?

 

[Guggie]

good post! Can I bring mine into a petshop or places that can check it for me? If not then where and how much did you pay for your UVB meter?

I don't know if you can do that or not - I know that LLLReptiles has one they use there, but I don't know if most have one or not. It is pricy - ~200.

 

[TylerStewart]

What I wish I had is a number that said "As long as you're higher than this, your torts are getting enough UVB."

Thanks for your help, Tyler!

I doubt anyone is going to tell you what "enough" UVB is.... There's constant debate whether they need UVB at all, so getting a firm opinion from someone about "enough" on a tool that almost nobody has is going to be quite a task!

What you can do is measure new bulbs and write it down. When they drop 30%, lower the bulb 3-4" and your readings will be similar to what the bulbs were when new. I use all double 48" fixtures mostly because they're super cheap at Lowes/Home Depot and with 48" length you can often cover multiple cages. The 48" length Reptisuns usually cost the same as 18" length, so you might as well be using longer ones. I always keep older bulbs and just run them side-by-side with a new one. When the newer one is getting old, throw out the oldest bulb, and put in one new one with the new-older bulb, if all that makes sense.

 

[EKLC]

I would take a few measurements out in the direct sunshine, shade, afternoon sun, etc and see how your bulb compares

 

[HtVic]

so at least 30% huh

 

[Guggie]

Chicago, March 20th

Sun at 3 pm - 175
Shade at 3 pm - 40
My 10 month old ZooMed MVB - 40

It's a bit annoying - I can't get the meter down to tortoise level, since it has to stand upright and it's about 3" tall - so the 40 is probably a bit less. I'm going to replace the bulb on Thurs, check the new value, and if I can go back to the old bulb.

 

[TylerStewart]

Chicago, March 20th

Sun at 3 pm - 175
Shade at 3 pm - 40
My 10 month old ZooMed MVB - 40

It's a bit annoying - I can't get the meter down to tortoise level, since it has to stand upright and it's about 3" tall - so the 40 is probably a bit less. I'm going to replace the bulb on Thurs, check the new value, and if I can go back to the old bulb.

The shade number and the MVB numbers aren't too different from what we get here. Nice to know that in full shade they're getting basically a similar amount of UVB to a MVB bulb (because in the sun here in the summer everything is at risk of overheating). We do most of our "sunning" of indoor babies underneath some big mesquite trees that give about 90% shade cover. Most of our outdoor tortoises are under shade cloth.

To get the meter "to tortoise level" you can just measure the distance then angle up the bulb and try to match it. We keep many of ours on wire racks so I can move the cage and stick the meter up through the bottom to get a reading "at tortoise level."

 

[Guggie]

To get the meter "to tortoise level" you can just measure the distance then angle up the bulb and try to match it. We keep many of ours on wire racks so I can move the cage and stick the meter up through the bottom to get a reading "at tortoise level."

Duh! Why didn't I think of that?!?!

Going to turn off the light now, let it cool down, and put in the new one. I'll let you all know what I find.

---

Going to turn off the light now, let it cool down, and put in the new one. I'll let you all know what I find.

The new bulb measures 100. I guess I'm leaving it in! Thanks all for your help. I'll update this over the next few weeks to see how it decays.

 

[Akronic]

i was told that even those screens can actually reflect some of the UV light back to the bulb, basically when using UV bulbs you dont want any kind of a filter between the bulb and the substrate/tortoise's shell.

 

[Guggie]

I have heard that too. i don't have any screen at all - just an open table.