HCA: Hermit Crab Association

I have a 20 gallon glass tank with an under tank heater.A vented lid I just cover if humidity level gets too low, and just a regular fish tank light fixture I use to bring up the tank temp. when it gets low. The problem is I'm fighting with this every single day. I have a salt water bowl, a salt water small (shorter than a dixie cup) size cup with a sponge in it, and a freshwater bowl in the tank. My bottom is a mixture of play sand and Eco Earth Coconut substrate that is 4-5 in. deep. I have 4 crabs in this. I have a stick on type thermometer on the outside of the glass in the middle of the sand so I know what temp. it is at all times and one inside so I know inside tank temp. and I have a hygrometer,also. If I can get the tank temp to between 70-75 degrees, it seems my humidity level goes down. Any suggestions???

Personally i have a 16 gallon tank with eco earth and vita sand and salt water and fresh water and a sponge in their salt water and a bigger sponge in the middle of the tank next to a center peice of coral. I alsoo have a vented lid. Its mesh kinda. I think what keeps my humidity in the best is i cover it with saran wrap every morning when i wake up i lift a corner or a side slightly so it can get fresh air flow bu i mainly keep it covered at night. I also have my heater on the side. I honestly dont have to spray the mulch that much because of the saran wrap. It makes the tank fog up and stuff. My main suggestion is cover your tank with saran wrap it works best for me and i can get the tank up to 80 and keep the humidity at 75

Here are my suggestions:Take the sponge out of the water (both of you) it serves no purpose other than to harbor lots of harmful bacteria(unless sterilized everyday)they can not drink from it.Use plastic wrap to cover your tank lids most of the way leaving a small space for air circulation.Make sure your sub (sand/EE) is moist sandcastle consistency.The uth under tank heater should NOT be under the tank place it on the side of the tank just at sub level. It should be rated for 3x the size of your tank so it can heat the air enough to be warm( like 60g or 2 30g). There are ways to insolate the uth pad so it becomes more efficient, but its easier to get the bigger uths, just ask.Your substrate is naturally going to be cooler so don't fret too much over that just try to get your above ground temps around 78-83 degrees F, if you have covered the tank and your sub is moist you shouldn't have any trouble with the humidity staying around 80% small dips in temp and humidity like +-2 is ok if more than that try to figure out what's causing it.Also check your thermometer and hygrometer sometimes they don't function properly giving false readings. There are ways to check them just ask if you don't know.Hope this helps.

I perfer to have my sponges in the tank. I love the sponge next to the coral because it is slightly shorter and they climb around on both things. I do boil them though and i actually have a few sponges. I rotate them. I take one out and put the dry steral one in whle i boil the wet one and i let that one dry then proceed to do this again. I think its common sense that something that stays wet 24/7 breaths mold and bacteria. So ive been doing this since i first got them even though no one told me to because it just made sense to me. Also i have the sponge that is next to the coral and not sitting in water in direction of the heather so it does help with humidity but it also goes through the boil rotation process.

Then you are one of the few who actually think about that. It is fine using it how you are the crabs may even eat a little of it which is ok its part of their nutritional requirements. Most people unfortunately leave it in the water bowl and seldom if ever sterilize it. It may help with the humidity some but the crabs can't drink off of it and if not changed well lets just say it gets pretty gross. Also it sucks all the water up leaving little to none in the bowl for the crabs to drink. This is why I suggested taking it out. However since you know to properly take care of the sponge by boiling or microwaving it that's perfectly fine.

I know I'm not supposed to be using a heating pad as a heater for my tank...but I haven't been able to find one big enough for my 20 gallon tank at the pet stores...is the heating really that bad to use if I check it constantly everyday? If my tank is 20 gallons...and if it's supposed to be on the side of the tank, what size heater do I need and how will that keep my sand warm? Keeping my sand warm is why I use the heating pad under the tank.

I've already addressed the substrate issue on your other thread here so please click the link and take a look, my post should be at the bottom of the page.As for your heat pad question you'd need a pad rated for an enclosure 3x's the size of the one your planning to put it on so for a ten gallon you'd need a thirty gallon rated heat pad to get the right temp increase.So for a twenty gallon you'd need a pad rated for fifty to sixty gallons to get the right temp increase.Because of the way these pads are designed it doesn't matter if your bottom mounting them or not they are not going to put enough heat out to properly heat your enclosure if you buy a pad rated for the exact size of your tank unfortunately.Bottom mounting is dangerous because the depth and dampness of the substrate required by our hermitcrabs act as an insulating barrier effectively trapping the heat being generated by the pad right next to the point of contact and the heat will continue to build up to dangerous levels exceeding 100 degrees which will bake a burrowed or molting crab and because the pane of glass is expanding due to the excessive heat if any cooler water should suddenly finds its way to the bottom the glass will try to respond by shrinking while its still expanding which will result in a shattering or cracking of the pane.I know some people who have had their bottom mounted heat pads get so hot from all the trapped heat that the pads literally melted down and burst in to flames these pads are notorious for melting or blistering if they are not properly vented which is a big reason why we only recommend back mounting as this gives the pad some space to vent excess heat preventing melting or blistering of the pad.If your tank sits right up against a wall you'll want to move it out away from the wall if you don't you could end up smothering the pad and cause it to ignite the wall.

Use flukers reptile moss that usually boosts up the humidity in your tank usually is sold at petsmart but make sure you take out the excess debris and make sure you wet the moss well