UVB Question

Scary Clam · Post by **Scary Clam** » Fri May 29, 2009 9:29 am

I am trying to prepare for getting Strawberries and violas some day, but I'm still new to crabbing. I want it to be perfect for when I'm ready. I know the Straws need a bigger and deeper salt water pool among other things, but I only have PP's now, so it's just a drinking (not bathing) dish. And I know they like the salinity higher, and they like it hotter and more humid. The violas, from what I've ready, should adapt pretty easily to the same conditions I have PP's in. I know that I have a lot to learn and prepare for, but I'm just working on the lighting at the moment...

I finally got a UVA/UVB light. It's a 20W from the Repti-Glo 5.0 series, by Exo Terra. I got this one because it was suggested for tropical environments. I have a 20L tank, and heat it 24 hours a day with Exo Terra's Night Glo bulbs. I've read different things on here, and different opinions about how much UVB they're supposed to get. Some say get the 2.0, some say get 3.0 for a tank this size (3.0 would be a different brand), and some say to get the maximum (8.0 or 10.0) because they aren't as effective as they claim. Looking at the graph of the 2.0 light, there was practically no UVB at all. I am also directly aiming it into the tank, because I know the glass top would filter out most of it, if I didn't. Is this overkill or was I confused by the previous posts?

Can I leave this light on all day? Should I leave it on all day? They dig a lot and hide a lot during the day, so they could hide if it was too much. Seriously, though, if it was really in a tropical environment, the sun isn't deciding to only put out UVB for a couple hours and then stop. It's an all day thing, and I'm trying to create a natural environment.

If anyone else has any thoughts or suggestions, or even tips for preparing for straws and violas, I'm open to 'em!

Thanks!
Ari

Post by **JediMasterThrash** » Fri May 29, 2009 1:04 pm

I don't think anyone really knows exactly what crabs requirements for UV light are, so everything is just speculation for now.

If the light is direct, probably a 2.0 or 3.0 would be sufficient. More if its going through a glass lid. I don't think a little more would hurt them.

The UV light should only be on during normal sunlight hours. Otherwise it will confuse their day/night cycles.

There is not much UV at night. The only sunlight we get at night is reflected off the moon

Scary Clam · Post by **Scary Clam** » Fri May 29, 2009 1:12 pm

Ok great, thanks! By all day, I meant just during the day. I shut it off at night. :)

Kilimanjaro · Post by **Kilimanjaro** » Fri May 29, 2009 2:07 pm

I use a UV light and I think it really helps with their day and night time schedules.

They have a good routine and know when it gets to be light and dark.

I hypothesize that this makes them less stressed and it gives them a natural cycle that they can rely on.

Guest · Post by **Guest** » Fri May 29, 2009 8:24 pm

UVA/ UVB does not penetrate through glass, so if you have a glass lid it's useless for anything but regular lighting.

Post by **JediMasterThrash** » Sat May 30, 2009 5:30 pm

80% of UVA will penetrate glass. Only 2% of UVB will.

UVA is mostly for day/night cycles. UVB helps make vitamin D3.

See my post about half-way down the page here:
viewtopic.php?t=40222&highlight=