How can I keep relative humidity in a tank between 70% and 85%?

Question

I need some way to regulate the humidity in a large glass tank full of hermit crabs, keeping the relative humidity between 70% and 85%. Getting it within the target range is easy enough, using certain substrates and moistening them. However, the only way to keep it within an acceptable range is to open and close the tank, which is difficult to do at night or when I'm not there! One would assume that there is some sort of regulator on the market for tank humidifiers and foggers, but this is not the case. Does anyone have any suggestions?

Answer 1

I house 65 hermit crabs in one very large glass aquarium with a glass lid and lights. The humdity stays constant at 79% relative humidty and I peak it at 83% when I see needed.

Misting the hermits can cause bacterial infections and will only temporarily fix the issue. They should not be living in a wet environment, as you may know, and misting them directly is a big no-no. Wet sponges house bacteria and mold and also is just a temporary fix.

I do not mist, nor do I have wet sponges. I do however have 2 large water pools in the tank. I also have a slit open in the glass lid right where the light sits, therefor no one can escape and it allows good air circulation and heat distribution. I do not use any type of equiptment to regulate the humidity at all, it is just a natural habitat within the tank.

Make sure your gauges have been properly tested and then any miss-measurements be noted or corrected by adjusting the gauges or noting the difference. You can calibrate it by following the directions on many online sites, just search for calibrating humidity gauges. NO humidtiy gauge is 100% accurate so you may be getting an imporper reading anyway.

They do make misters and foggers but that is not accuarte as far as their natural environment and it will run the chanse of bacterial gill infections which can kill them. (they have very sensitive modified gills)

Also, you must allow air exchange and some air flow. Hermit crabs require daily care, they are not a set it and forget it kind of pet. Misting, spraying and that kind of thing does nothing to make a sustained environment.

We use dry natural play sand, coral tiny gravel by the water pools, we do not pre-wet or spray the sands, we have large 2-3 cup holding water pools and about 4 food dishes. We change the water every 3-4 days and the food gets changed out every other day.

They will wet the sand to their liking many times, by filling thier shells with water and dumping it where they want it. They do not always live on the coast but many times travel far off shore, 3 miles sometimes, so do not be too concerned with a humdity of 70% sometimes but 76-78% would be perfect. So they are not always in humid environments their entire life, when they become small to meduim and larger size they only stay on the beaches for breeding or becuase of lack of safe places to travel or because of lack of natural feeding areas.

So, try larger water pools, a soild lid but allow a bit of venting, even 1/4 inch will do in many cases.

Answer 2

how big is the tank and how long has it been set up? If it's a new set up it takes about a month for things to regulate after that you won't have to play with it as much. For right now you can play around with different sized things to prop the lid open a little. I use the small sponges for the water bowls to prop mine open. I have glass lids on my 55 gal and if the humidity is to high then i move the sponge back further on the opening half of the glass lid to let more humidity out, if it's to low then i move it more towards the front to let less out. (I have the plastic part of the glass versa top on the front side for this purpose. you should always have a small opening for air circulation, if that drops your humidity then you have several options.

you can make a bubble pool with an air hose and air stone and air pump in your largest water bowl.

you can add a damp moss pit

or you can make a humidifier the directions to do this are at www.hermitcrabassociation.com in the diy section

to high or too low humidity won't hurt them in the short term, so they are all right if it goes up or down over night or while you are away from home.

I highly discourage using a mister as that will soak your substrate and flood your tank. A few people have tried it with the flooding results. Hand misting with a misting bottle is fine just don't spray the crabs, it can stress them.

Answer 3

Open water bowls would help a little bit. Also how well ventilated the tank is can ahve an effect. If you have a screen top covering the whole thing try covering a portion of the screen keeping the moisture in. If humidity is that high I'd suggest something like plastic that wont rot from the high levels. If you want to invest some time, set something up so that the cage is on a timed mister.

Answer 4

Do you have a tank mister? There's one called Habba-Mist that can be set to mist the tank at programmed times and for programmed lengths of time. These aren't cheap, but may be good for your situation: http://www.thatpetplace.com/pet/product/productInfo.web?infoParam.mode=1&infoParam.itemKey=204440

Another thing you could try is to use an air pump with tubing to an airstone and put this in a large water container (one of their soaking dishes?) - as the water bubbles, it will evaporate more quickly, especially if near a light (heat source) in their tank. Also putting (additional) sponges in their water will help the water evaporate as it is absorbed through the sponge.

You say you need to open and close the tank - can you prop a corner open with a pencil or something small if you're getting too much humidity?

Hope these suggestions help - you'll just have to experiment till you find what works in your set-up.

Answer 5

My father owns a tropical reptile and fish store in Boston. Normally to maintain humidity in a terrarium we've used a misting bottle. You can buy them at like home depot. Its like a windex bottle, the way water sprays out of it. Just set it to mist instead of stream. The water in mist form will evaporate quickly into the air so use it in abundance, dont soak things but you can get the surface of the tank and rocks wet. This will definitely humidify your tank.

Answer 6

It would be great just to have a shallow dish of water for the hermit crabs to soak in... Having water around the tank would raise the humidity. But be sure to change this water often! If you want the humidity higher (hermit crabs love this), then it would be a good idea to take a regular spray bottle and spray water onto the inside walls of the tank. Good luck with your pets! :)

Answer 7

You can mist by hand, you can buy a fountain, you can add a bowl of water with an air pump, you can add a glass hood if you don't have one now and you can purchase a humidifier.

Answer 8

well theres a mister wich is the habba-mist and a foger that i dont know the name of. www.lllreptile.com