relationship between lighting and calcium??

tonycoenobita · Post by **tonycoenobita** » Mon Sep 04, 2006 1:00 am

Is there any relationship between lighting and calcium for crabs??
Lighting will help crabs easy to absorb more calcium?

i always afraid lighting will lead the humidity very low..........

Guest · Post by **Guest** » Mon Sep 04, 2006 1:56 am

I am actually not sure if it helps them digest it but in my opinion light does a lot for them. I would guess it could help. I think the light shouldn't drain the tank of humidity unless it was a strong one. There are still many ways to keep the humidity up.

Guest · Post by **Guest** » Mon Sep 04, 2006 2:44 am

I know in reptiles vitamin D3 (cholecalciferol) is needed to metabolize calcium, and is made in skin by contact with UVB rays. I have never come a crossed any study made of this connection with a crustacean exoskeleton, but it may be reasonable to assume it would work the same way.

tonycoenobita · Post by **tonycoenobita** » Mon Sep 04, 2006 4:33 am

Then what light show I use?

HERMEZ · Post by **HERMEZ** » Mon Sep 04, 2006 7:25 am

tonycoenobita wrote:Then what light show I use?

reptisun has UV rays that are natural--although thru glass it is diminshed but if thru a screen or direct that would work

research is also proving that more direct sun helps injured crabs heal.

Guest · Post by **Guest** » Mon Sep 04, 2006 2:56 pm

I wonder how it would effect my tank conditions if I let some UVB rays into the top without the glass there and if I'd see any benifits to it. I may try an experiment.

tonycoenobita · Post by **tonycoenobita** » Mon Sep 04, 2006 9:36 pm

i also afraid of this. UVA ray will lower the humidity of the tank.
I am worry about it.

How about DAYLIGHT BLUE Reptile Bulb?
Could I use this bulb in the tank.

Guest · Post by **Guest** » Tue Sep 05, 2006 1:51 am

I have been using ZooMed ReptiSun UVB bulbs in my tanks for over a year now. I used to have just "bright daylight" fluorescents for aquariums, but I gave those to hubby for his fish.

I use the lights about about 10 hours a day, over a glass top, which reduces some of the UV absorbtion, but the humidity stays up. I have a 2.0, 5.0. and a 7.0. My observations are that more crabs choose to "perch" in the light, and I have had fewer deaths of unknown causes, and fewer surface molts (just one which was actually my fault).

I do believe there are benefits including, but not limited to, calcium absorbtion. Using a timer, I can create a more natural day/night sequence. They can choose to hide by day if they wish. But the longer I have any individual crab, they less they hide by day.

tonycoenobita · Post by **tonycoenobita** » Tue Sep 05, 2006 5:16 am

Thank you very much , then mean light is good for them.

But what is the different between UVA and UVB??
some people said it is good to buy UVA, but some said UVB.......

I found that ReptiSun 2.0 is most suitable for land hermit crab??
coz it is "Designed for use with snakes, amphibians, invertebrates, birds, and fish."

Post by **JediMasterThrash** » Tue Sep 05, 2006 9:31 am

Hmm. I had made a great post on UV-light on one of these forums a while back, but it seems to be missing now. It probably should have been archived. I'll try to summarize it again.

UVA:

Here's some info about UVA:
http://www.emaxhealth.com/66/7215.html

UVA is mostly transmitted through glass and screens (and is not blocked by normal sunscreen and it penetrates deeper into the skin and causes aging and melanoma). Our crabs are probably a small amount of natural UVA even indoors in crabariums. A UVA light on a crabitat will provide extra.

Reptiles see in the UVA range, so they have increased activity when exposed to UVA.

UVB:

Here's my source on the UVB-info
http://www.uvguide.co.uk/index.htm
Basically:
chicken wire (very coarse mesh): Reduces UVB by 7%
mesh: Reduces UVB by 15-30%
flyscreen (very fine mesh): Reduces UVB by 50%
Aquarium glass: Reduces UVB by 98.5%
Plexiglass acryllic: Reduces UVB by 20-40%

Combination of house windows and aquarium means that the hermit crabs are getting absolutely 0% natural UVB. If you place a UVB light ontop of a glass or plastic lid, likely only 2% of the UVB is reaching the crabs.

Reptiles use UVB to synthesis Vitamin D3

So, in order to effectively use a UV-light, you need to have the light over a screen or open-portion of the top of your crabarium.

As for lights reducing humidity, it's not something you have to worry about if done right. The heat from lights increases the saturation point of the air, so for a given amount of water vapor in the air, the relative humidity will decrease. However, a properly setup crabitat should have good pools of water and a moist/sandcastle substrate. The radiation from the light will evaporate more water from the pools and surface, increasing relative humidity.

The hotter air will increase air pressure, so the air will try to escape out of the tank, rising out of gaps in the lid. You'll simply have to reduce the gaps in the lid. I always have my tank lid proped open about 15-degrees (PI/12 radians), and the relative humidity stays 75-80%. Of course it helps that I have two tropicaire humidifiers running to keep moist air coming in. But for my ISO, I just prop the lid or de-prop the lid as necessary to regulate the humidity.

The only thing you'll have to do is refill the water pools more often, since they'll evaporate faster, and maybe occasionally mist the substrate (or poor small amounts of water down the sides) to keep the substrate moist.

15w fluorescent UV-lights add a negligible amount of heat. You should put them on timers so that the only come on during daylight hours so as to keep proper day/night cycles for your crabs.

Some crabs will only come out at night. But I've always got a number of crabs that enjoy basking. They will climb up and get as close to the light as they can and sit there all day.

And on top of it all, crabs need higher temperatures that most people's houses provide, and overhead lighting (in my opinion) is the best way to provide temperature increases. Moonglo/nightglo bulbs can provide 24/7 heat, and can be found in 15 and 25w packages so as not to overheat/overevaporate the tank.

And just because I'm trying to set a guinness book of world records here or something, I'd like to mention that my original pair of 25w moonglos are still running! They've been on continuous for 24,500 hours now! They were only rated for like 2000.

For heat, it's fine to go through the glass. Some people have had their glass lids crack from the heat, but mine hasn't yet. Keeping the glass lid over the tank also helps prevent moisture from escaping.

However, you'll need to have the UV light over a mesh or open part. The hood should provide enough enclosure so as to prevent much air from escaping.

BAB · Post by **BAB** » Tue Sep 05, 2006 9:59 am

Okay... so we need both UVA and UVB lights then?

How can I tell the difference with the bulbs?!?

I currently only use SunGlo and NightGlo bulbs... but they are being filtered through glass.

WOW Everyday soemthing new on this board pops up that I need to adjust in my tank.

tonycoenobita · Post by **tonycoenobita** » Tue Sep 05, 2006 11:23 am

agree with BAB.
->we need both UVA and UVB lights then???

Could you (JediMasterThrash) tell me which brand of UVA light and UVB lgiht are good.

Or could you post some photo for us to have a look?

I just know these bulb/light in Hong Kong
>ReptiSun 2.0
>ReptiSun 5.0
>Nocturnal Infrared Heat Lamp
>NIGHTLIGHT RED Reptile Bulb
All are Zoomed product.

Guest · Post by **Guest** » Tue Sep 05, 2006 3:01 pm

Are lights absolutely needed?

Guest · Post by **Guest** » Tue Sep 05, 2006 6:55 pm

ALHC wrote:Are lights absolutely needed?

I was wondering the same thing. We have all been talking about how lighting helps with their coloring, & what lighting is best. But in the wild, hermits don't come out of hiding until dusk. Most dig down for all of the daylight hours. So really, how much light do they have in the wild?

I, too, use the Repti-Sun 2.0 for daylight hours (2 of the 18" on my 55-gal.) And at night, I use a Moonglow & a Red night bulb. But I really wonder if I am doing it for them, or so I can see them!

BAB · Post by **BAB** » Tue Sep 05, 2006 7:58 pm

*Kathy* wrote:But in the wild, hermits don't come out of hiding until dusk. Most dig down for all of the daylight hours. So really, how much light do they have in the wild?

I don't have the crabbies in my tank hiding all day. Do they REALLY hide all day in the wild?