Lights and Heating in the Hermit Crab Tank
I’ve been reading a lot of posts on the HCA that lights are bad for hermit crabs; this is not true. Light it good for hermit crabs; it’s bad when a bulb is used with too high a wattage for the tank. Using a desk lamp to heat the crabitat is not a good idea, it should only be used as a temporary heating device. Desk lamps can over heat the crabitat and so can high wattage reptile lights.
That being said how do you heat the crabitat?
Some people use Under Tank Heaters (UTHs), some people use lights only, and some use a combination of both. A UTH is like a heating pad that sticks to the bottom of your tank. Some don’t like UTHs at all because they feel that heating the sand from the bottom is unnatural.
I personally use a UTH and lights, I’ve found a combination of the two works for my tanks. There is really no absolutely right or wrong method; the important thing is that you maintain temp and humidity in the 74-78 range (this may vary depending on the species). This is why gauges are so important!
Just to clarify, I have glass lids on all of my tanks, the lighting fixtures sit on top of the glass lids. One of the light fixtures I have to raise with some wooden slats from Michael’s. You will see the fixture in one of the pictures below. This is the only fixture that I have to raise, otherwise they sit directly on the glass.
Lighting
Lights are great for warming the air. You can use day glo or night glo lights or a combination of both. The thing that you want to be careful about is that you don’t get a light with too high of a wattage for your tank size. If you have a 10 gallon tank, you shouldn’t use more than a 15 watt bulb. If you have a bigger tank you can use a higher wattage. For example, I use a 60 watt bulbs on my 55 gallon tank. If you use a lamp that has too high a wattage you can harm your crabs because the humidity tends to drop and the hermit crabs can overheat.
On my 29 gallon tank I use the two hoods above. The black hood holds two incandescent bulbs and I got it at a local pet store for $20.00. I started with two 25 watt night glo reptile bulbs, but when one burnt out I increased the wattage on one side to 40 watts. What a difference that made! My straws love the additional heat and my humidity is remaining stable. I frequently find them sitting right under the 40 watt bulb. This little fixture gets hot; I had to put some wood slats that I found at Michael’s (wood craft section) under the hood to raise it by about a 1/4″ inch. Without the wood slats the hood cracked my glass.
In the brown hood I have one ReptiSun 2.0 Fluorescent. This has a nice warming effect on the tank during the day. I also use one of these repti-sun bulbs on my 55 gallon.
On the 55 gallon I use a combo light that I got on ebay with the bulbs for $40.00. It holds two incandescent (day & night glow) and one fluorescent (repti-sun 2.0). I have a 60 watt day glo bulb that’s on during the day, a 60 watt night glo for overnight, and a Repti-Sun 2.0 that’s on during the day. The combo light covers half the tank.
I also use a regular aquarium hood on the other half of the tank without special lighting.
My exact combination won’t work for everyone. I use glass lids, I have Tropic Aire Humidifiers, and I use air stones in all of my pools, so I don’t have any problems with low humidity. With my current tank setups I’ve been maintaining stable temps and humidity in the 78-81 range.
If you decide to use lights, start with a low wattage bulb, see how it works on your tank and add a higher wattage if necessary. If you want to provide more warmth at night, use a night glow bulb. If you want to provide more light and warmth during the day, consider using a day glow bulb and/or a repti-sun 2.0 fluorescent. I have seen a definate increase in activity in my hermit crabs by using a combination of lights on my tank.
Tomorrow I’ll try to write a post about the benefits of air stones in your crabitat.
Edit 10/14/05 - We have been discussing lights and heating a lot on the HCA forums. Here is some information I recently posted about 10 gallon tank hoods:
There are hoods that you can find for 10 gallons, but I don’t think Fluckers makes any. Some regular 10 gallon aquarium hoods will hold incandescents, so that’s an option. I use a regular 10 gallon, incandescent hood on my gallon ISO. The only problem is that you have to spray the tank more often. You could us glass between the hood and and tank and that would eliminate the need to spray.
The hood that I have on my 29 gallon (you can see it in the second picture in this post) would fit a 10 gallon (it would require a glass lid). Unfortunately, there isn’t a brand name on it, but you can see it in the second picture above. I found this light at a family pet store in Fremont. I would recommend that you look at your smaller stores for this type of light; smaller stores tend to carry stuff that the chains don’t have. Here is a regular 10 gallon incandescent hood at Doctors Foster and Smith.
20″ combo hoods are available here at 4 little Pets and Doctors Foster and Smith.
For daytime light I have this tiny hood for my five gallon. Since it uses the Dessert Sun 7 fluorescents it puts out enough heat for the little tank during the day.
I would really like this Reptile Slider hood for my big tank but my hermies are spoiled already. Maybe if my current hood breaks. 
You may also find this article on heating helpful http://www.crabbytalk.com/09152005/the-temperature-of-the-crabitat/
