HCA: Hermit Crab Association

Just bought an 11inch x 17inch UTH and I was just wondering if it is better to place it under the tank...or mount it on the backwall. My tank is 36inches long and 18inches deep so it won't cover the entire tank (I will still have cooler spots), but I want to make sure I put it in the right spot as you cannot remove it once it is secured into place.

My worries are that it will heat the substrate too much and fry my crabs (I have moist ecoearth and calcisand with some reptile fir bark chips that is different deepness in the tank) or if it is on the back wall that it won't radiate the heat across the entire portion of the tank.

So, I am asking the people with experience...which is better? Currently I am using a heat lamp, but it is drying my tank out and keeping the humidity low. When I remove the lamp and cover the screen with plexiglass (leaving air spaces on either sides of the tank) than the humidity remains good but the temp goes down. That is why I bought a UTH. Now I just need to make sure that i mount it in the right place...because once it is on...it says it is permanent.

Please, Please help the newbie!!!!

I really don't care for UTH's. Lights are the way to go for heating, much more effective in my opinion, I think you should try to heat the air not the substrate. but I have had better luck mounting them on the side. Heating from the bottom seems unnatural to me because, crabs natural instinct is to dig down when they become too warm.

Also: If your sand is 3"+ (which it should be) a UTH will not penetrate very well, and thus not produce enough heat.

So-in my experience; the side generally works better but I only briefly used a UTH before I switched to lighting. So I really don't have that much experiance with them.

I had mine under the tank, then i moved it to the sides, i had better results i think with it under the tank, when it was on the side i didn't see much of a temp change.

I have mine on the inside of the tank under the substrate about 1/2" from the bottom of the tank on a later of sand. This keeps the substrate nice and warm and the temperature is very stable. The crabs seem really happy with it, they simply don't dig close to it as they know it's too hot for them. They also enjoy climbing the cable and falling off.

I dont advise putting it on the inside of the tank for obvious electrical reasons and they do get quite hot. I actually am going to move my UTH from under the the side simply because they cant dig when its under the sand , I have a 40g UTH for my 29g, and its quite powerful. I also have a 20g UTH side mounted that helps alot, just keep the top covered

I have some on the bottom and some on the side...

In my 10 gallon tanks... I have them on the bottom.. I use the smallest UTH heaters.. and I have no problems with heat or humidity... mine are all 1/2 half play and and 1/2 EE... and iN the smaller 10's they are on the sand side bottom....

Now in my larger tanks.. my 100 and my 30, I have them on the outside back.. I do have more problems keeping the heat up....but no problems with humidity... I use heat lamps as needed to add heat....

I'm in North Florida.. with central air conditioners running all the time...so maybe that makes a difference?

I have decided to mount it on the back of the tank...but I have already noticed that it isn't really keeping the temp up past 70degrees. I do have a heat lamp, but then when I want to use it I have to remove some of the plexiglass on top of the cage and then the humididy gets out. Is 70 degrees too cold? I am putting my space heater on in the room at night and it is keeping at 77-80 degrees, but the space heater is very expensive to run.

In Winnipeg, Manitoba we have VERY dry, hot summers..so the air conditioner es a MUST in our house. It isn't on yet, but I am starting to get worried about when they do come on this summer.

You could try a smaller watt size. What type of bulb are you using? Is it a black light or a bulb meant for home lighting?

Currently I have a 50watt Red Light (I believe it is an infared light because I bought it for my leopard gecko a long time ago). I did by a 50watt black light (moonlite or nitelite) but it isn't powerful enough. When it is on...I cannot see a thing inside of the tank. With the red light on I can see VERY well. But it does dry out my tank. My boyfriend wired it into a dimmer switch (rheostat) so that I can turn it up or down, and that seems to help a bit. I just wish that the UTH I have mounted on the side of the tank was powerful enough so that I wouldn't have to worry about anything else.

I have found, and many others here, that UTHs not mounted on the bottom do little for heat. If you mount a UTH on the side of the tank the heat will rise out of the lid before it even can do its job. I suggest remounting it on the bottom. During the winter months I have to depend on my UTH and a sunglo bulb during the day and a infrared heat bulb at night.

My in under, but right below my water dishes since I need to dry it a bit.l

I am hearing so many different things from so many different people. I have heard that if the UTH is UNDER the tank, then it keeps the tank warmer...BUT...it can burn the crabs when they dig under the substrate.

I have also heard that if the UTH is on the SIDE of the tank, then it won't keep the tank warm enough, as the heat will just escape out of the lid without heating the tank...BUT...it is a safer way to heat the tank.

I am so confused. It doesn't seem to be heating the tank very well with it being mounted on the wall is it is right now. Some of the crabs have chosen to dig in the substrate close to the heating pad, and others are still sticking to parts of the tank without the heating pad near it.

The heating pad is supposed to be a permanent one, but maybe I will be able to unstick it and try the bottom of the tank if that is what everyone suggests.

Will the heating pad burn the crabs or are they smart enough to not dig down as deep? I have also heard that a heating pad mounted on the BOTTOM will not penetrate through 3-6inches of substrate. I AM SO CONFUSED!!!!!!!!!! I guess that only trial and error will help me in this case (just as long as I am in no danger of burning my little crabbies). I will NOT put the heating pad on the INSIDE of the tank. Just to be safe!

I prefer having my UTHs on the bottom. Side mounts are nice for crabs when they want extra warmth, but they only heat the substrate for no more than an inch away.

If you put your UTH om the bottom it's best if you put them on small blocks of wood or even Legos. This way the air circulates, so there is less of a chance that something electrical may happen.

If you're afraid one of your crabs will moult right above the heater (they're really not that stupid but you never know) put a layer of gravel in the tank over the heater. That way your crabs can't get all the way to the bottom.

By the way, I'm charging now for the great advice. That'll be or

hermiegal wrote:I am hearing so many different things from so many different people. I have heard that if the UTH is UNDER the tank, then it keeps the tank warmer...BUT...it can burn the crabs when they dig under the substrate.

I have also heard that if the UTH is on the SIDE of the tank, then it won't keep the tank warm enough, as the heat will just escape out of the lid without heating the tank...BUT...it is a safer way to heat the tank.

I am so confused. It doesn't seem to be heating the tank very well with it being mounted on the wall is it is right now. Some of the crabs have chosen to dig in the substrate close to the heating pad, and others are still sticking to parts of the tank without the heating pad near it.

The heating pad is supposed to be a permanent one, but maybe I will be able to unstick it and try the bottom of the tank if that is what everyone suggests.

Will the heating pad burn the crabs or are they smart enough to not dig down as deep? I have also heard that a heating pad mounted on the BOTTOM will not penetrate through 3-6inches of substrate. I AM SO CONFUSED!!!!!!!!!! I guess that only trial and error will help me in this case (just as long as I am in no danger of burning my little crabbies). I will NOT put the heating pad on the INSIDE of the tank. Just to be safe!

Do not be confused as I have already answered your question. Mounting a UTH on the side or back of your tank will do little for heat. If you mount it on the bottom it will do more for heat. Your crabs are not stupid so they won't get burned by the UTH. I have been doing this for 3.5 years and never once has that been a problem.

ok...thanks again for the advice!!!