HCA: Hermit Crab Association

I have a UTH that seems to be in good working order. But I can't get the warmth up enough in my crab's home. Is there a way I can help make it warmer for my little guy? I know it's been colder here for us too (dipping below 40 at night, then up to 60s during the day)...it's been a weird beginning spring here in Tennessee!


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What does your thermometer/hydrometer read? Do you have a gauge in your tank to read the temperature and humidity?

You can insulate the UTH with foil if it is an Ultratherm. I know there are other brands that can be; but I always forget which ones. I know @Wodesorel knows but for some reason they always slip my mind.

My UTH is insulated with foil and electrical tape. It's always in the low to mid 80's in my tank(s). (55 gallon and 30 gallon).

Some people have had success with some reflective foil insulation stuff they've gotten at Home Depot or Lowes, others have used foil then cardboard.

soilentgringa wrote:What does your thermometer/hydrometer read? Do you have a gauge in your tank to read the temperature and humidity?

You can insulate the UTH with foil if it is an Ultratherm. I know there are other brands that can be; but I always forget which ones. I know @Wodesorel knows but for some reason they always slip my mind.

My UTH is insulated with foil and electrical tape. It's always in the low to mid 80's in my tank(s). (55 gallon and 30 gallon).

Some people have had success with some reflective foil insulation stuff they've gotten at Home Depot or Lowes, others have used foil then cardboard.

How do you insulate it? Are there some guides on how to insulate?
Thanks!!

Giner13 wrote:How do you insulate it? Are there some guides on how to insulate?
Thanks!!

Before running off and insulate, make sure your heater can handle it. Some are prone to melting or other potential fire hazards if insulated. All you need to do is just sticky tape (or whatever will stick on the insulating material) the foil to the glass. Sit back and relax.

They make some stuff--I think it is for insulating pipes--that you can get at Lowe's or similar places. It is two layers of silver Mylar, with air bubbles in between (kind of like mylar "bubble wrap"). This stuff is super for insulating tanks, and can be saved and re-used year after year.

We keep the 90g wrapped on three sides (sides and back) from fall into spring; during particularly cold snaps in the winter I have a piece cut to wrap the front, too. I just tape it on with wide masking tape. It is perfect for keeping as much heat as possible in the tank (because of the reflective property, like aluminum foil), and because of the air pockets, it also reduces heat transfer between the surrounding air and the tank. I "inherited" mine several years ago, so I don't know how much a roll of it costs, but because you can cut it to fit whatever size your tank is, and roll it up and store it easily when you don't need it, then bring it out and re-use it when you do, I highly recommend it, for anyone whose house is regularly going to be colder than crabs can stand.

For the 90g, it isn't wide enough to completely cover from top to bottom of the tank, but since the bottom of the tank is all deep substrate, and once substrate is warm, it is itself an excellent insulator, I don't worry about covering all the substrate. For winter, I do put a piece along the bottom (underneath) of the tank to reduce heat loss from the very bottom of the substrate, but the substrate itself is pretty good at keeping its own warmth, and they expect to be able to dig down to somewhat cooler temps.

NOTE: this mylar "bubble wrap" stuff is SUCH a good insulator, you need to keep a sharp eye on your temps for the first day or two when you first put it on, because you could quickly see a really sharp spike in temp (which will also bring your relative humidity down sharply); you need to watch and regulate whatever your heat source(s) are, until you get it balanced well, taking the insulation into account, again.

Thanks guys!
However I don't think mine is a brand I can insulate safely.
I do have plastic wrap around my screen lid...should I replace that with tin foil for starters?


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You can just cover the plastic wrap WITH foil, if you like (I don't like having aluminum--I'm assuming you really mean aluminum foil, not actual "tin" foil--anywhere where the crabs might be able to touch it, and directly covering a mesh lid with it, they could definitely poke through the mesh and maybe tear bits off the foil). Also, if you don't think you can cover your UTH, you can use the mylar bubble wrap everywhere but directly over your UTH; it is very easy to cut with scissors to whatever configuration you need.

DragonsFly wrote:You can just cover the plastic wrap WITH foil, if you like (I don't like having aluminum--I'm assuming you really mean aluminum foil, not actual "tin" foil--anywhere where the crabs might be able to touch it, and directly covering a mesh lid with it, they could definitely poke through the mesh and maybe tear bits off the foil). Also, if you don't think you can cover your UTH, you can use the mylar bubble wrap everywhere but directly over your UTH; it is very easy to cut with scissors to whatever configuration you need.

Thanks! Given me some ideas I can definitely use!

I covered my plastic-wrap-covered screen lid with foil yesterday, leaving a narrow strip uncovered.
That combined with my ceramic-pot-over-damp-sponge DIY humidifier, helped take my humidity to between 80-85.....heat has raised to 75, but shouldn't it be higher for the heat as well?


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75 is the minimum for PP's--so you are good if it doesn't drop any lower at night. If you could squeeze a few more degrees out of your setup, that would be golden!

The comfort range for PP's is:

Temperature between 75 and 85 degrees Fahrenheit (they don't mind if it gets a little higher during the day, but ideally it really should not drop any lower than 75; prolonged temps under 70 are not survivable long-term).

Relative humidity between 75 and 85% (again, higher than this on occasion is fine--in the wild, sometimes it rains, and then the relative humidity is 100%!--but keeping it in this range most of the time should be the goal; humidity less than 75% begins to suffocate them, since they breathe with modified gills and must have enough moisture in the air in order to extract oxygen from it).

So, remembering 75 to 85 for both readings (if you are American ) makes it easy. If you're a Celsius sort, you have to remember two sets of numbers, sorry.

DragonsFly wrote:The comfort range for PP's is:

Temperature between 75 and 85 degrees Fahrenheit (they don't mind if it gets a little higher during the day, but ideally it really should not drop any lower than 75; prolonged temps under 70 are not survivable long-term).

Relative humidity between 75 and 85% (again, higher than this on occasion is fine--in the wild, sometimes it rains, and then the relative humidity is 100%!--but keeping it in this range most of the time should be the goal; humidity less than 75% begins to suffocate them, since they breathe with modified gills and must have enough moisture in the air in order to extract oxygen from it).

So, remembering 75 to 85 for both readings (if you are American ) makes it easy. If you're a Celsius sort, you have to remember two sets of numbers, sorry.

Haha good for me only one set of numbers!
I'd like to get a few more degrees for temp, but brainstorming so far hasn't yielded many ideas. Any thoughts?

How long has your substrate been in the tank, and when you originally moistened it, did you warm the water you used to moisten it with? If the substrate wasn't "pre-warmed" by being moistened with warm water, and it's only been a few days since you set it up, what you may be waiting for is for the "thermal mass" of the substrate to get warm. Depending upon how much substrate you have (and for hermit crabs you should have a lot, they need deep substrate), this can take a LONG time (just one of many reasons why it is always best, if you can, to set up and balance the tank for a week or two BEFORE putting any crabs in).

So that's the bad news about substrate--if it's cold, it takes a LONG time to warm up, and while it is doing that, it is fighting the warming up of the entire tank. The good news is, once it IS warmed up, it then becomes your ally in keeping the tank warm, because again, that large "thermal mass" resists changing its temperature, either way.

So if your set-up is less than a week old, that may be the main problem; waiting for substrate to warm. If so, here's what I did to quickly warm the cold substrate in our iso, when I was panicking trying to set it up quickly and did not think to pre-warm the water to moisten the substrate:

I took a Pyrex measuring cup (special glass designed to be able to deal with very hot temperatures). I put a little bit of water (use filtered spring water or dechlor water, whatever you use that is safe in the tank) in the bottom of the Pyrex measuring cup, then filled the tea kettle with safe water and brought that to a boil. I dug a hole and nestled the Pyrex cup down in the substrate, poured the boiling water into it, and let it sit there for a half hour to an hour, dispersing the heat into the surrounding substrate. Once the water in the cup was just lukewarm, I took it out carefully (the substrate was already moist, so didn't need more water to get flooded, but if I did spill a little I knew that would be okay since it was safe water), then repeated the process with freshly boiled safe water in another hole in the substrate. I did this several times in several places, and the whole substrate (in a 10g iso) was warm within about two to three hours. If you have a crab in the tank and don't have an alternative place to put him while this is going on, you will need to isolate him in some way (put him in a little KK inside the tank, away from where the hot water is warming the substrate, or something); because very hot temperatures or exposure to steam will cause irreparable damage to a crab.

I guess you could also use those hand warmers or other kinds of "warming packs," nestled down into the substrate in different places, to help warm it, the same way. However, I don't know about the safety of exposing the crabs directly to whatever those packs are made of, so I might put them in a ziploc bag or something (if that is safe--not sure--people more familiar with those will have to chime in here), and again isolate the crab(s) away from the warming areas while it is going on.

You could try just wrapping the substrate level of your tank with those hand warmers, on the outside. That would likely take longer than putting them right down in the substrate, but it would help some, especially if you put foil or the mylar "bubble wrap" stuff on the outside of the warmers, to help reflect their heat inward.

If you do any of these things, and there's no alternative place to put the crab(s) while you are trying to warm the substrate, keep a careful eye on temps in the tank, as well as relative humidity, to make sure it isn't getting TOO hot.

And remember this when/if you ever upgrade: you'll save a LOT of time getting the tank balanced if you remember to moisten the substrate with warm water to begin with, instead of cold!

DragonsFly wrote:How long has your substrate been in the tank, and when you originally moistened it, did you warm the water you used to moisten it with? If the substrate wasn't "pre-warmed" by being moistened with warm water, and it's only been a few days since you set it up, what you may be waiting for is for the "thermal mass" of the substrate to get warm. Depending upon how much substrate you have (and for hermit crabs you should have a lot, they need deep substrate), this can take a LONG time (just one of many reasons why it is always best, if you can, to set up and balance the tank for a week or two BEFORE putting any crabs in).

So that's the bad news about substrate--if it's cold, it takes a LONG time to warm up, and while it is doing that, it is fighting the warming up of the entire tank. The good news is, once it IS warmed up, it then becomes your ally in keeping the tank warm, because again, that large "thermal mass" resists changing its temperature, either way.

So if your set-up is less than a week old, that may be the main problem; waiting for substrate to warm. If so, here's what I did to quickly warm the cold substrate in our iso, when I was panicking trying to set it up quickly and did not think to pre-warm the water to moisten the substrate:

I took a Pyrex measuring cup (special glass designed to be able to deal with very hot temperatures). I put a little bit of water (use filtered spring water or dechlor water, whatever you use that is safe in the tank) in the bottom of the Pyrex measuring cup, then filled the tea kettle with safe water and brought that to a boil. I dug a hole and nestled the Pyrex cup down in the substrate, poured the boiling water into it, and let it sit there for a half hour to an hour, dispersing the heat into the surrounding substrate. Once the water in the cup was just lukewarm, I took it out carefully (the substrate was already moist, so didn't need more water to get flooded, but if I did spill a little I knew that would be okay since it was safe water), then repeated the process with freshly boiled safe water in another hole in the substrate. I did this several times in several places, and the whole substrate (in a 10g iso) was warm within about two to three hours. If you have a crab in the tank and don't have an alternative place to put him while this is going on, you will need to isolate him in some way (put him in a little KK inside the tank, away from where the hot water is warming the substrate, or something); because very hot temperatures or exposure to steam will cause irreparable damage to a crab.

I guess you could also use those hand warmers or other kinds of "warming packs," nestled down into the substrate in different places, to help warm it, the same way. However, I don't know about the safety of exposing the crabs directly to whatever those packs are made of, so I might put them in a ziploc bag or something (if that is safe--not sure--people more familiar with those will have to chime in here), and again isolate the crab(s) away from the warming areas while it is going on.

You could try just wrapping the substrate level of your tank with those hand warmers, on the outside. That would likely take longer than putting them right down in the substrate, but it would help some, especially if you put foil or the mylar "bubble wrap" stuff on the outside of the warmers, to help reflect their heat inward.

If you do any of these things, and there's no alternative place to put the crab(s) while you are trying to warm the substrate, keep a careful eye on temps in the tank, as well as relative humidity, to make sure it isn't getting TOO hot.

And remember this when/if you ever upgrade: you'll save a LOT of time getting the tank balanced if you remember to moisten the substrate with warm water to begin with, instead of cold!

Great!! I didn't think/know to pre warm the sub before putting in, but makes sense & I'll keep in mind next time I upgrade. I have some little hand warmers and those may be easier for me to use vs. the measuring cup method. And I do have a place to keep him for the few minutes that that takes place!!!
I'll be keeping an eye on the temps & I'll have a soon chance to get that done. I figured this is the reason he is staying buried so much lately & I can tell he is not down for a molt yet.