First Time Owner to 4 Crabbies!

[kayepaye]

So I recently rescued 5 hermit crabs, unfortunately one of them passed away. They're currently living in a 10G tank with a heat lamp, in a completely unsuitable setup.

So I picked up a 40G tank last night, it was on clearance for $97 and came with a screen top already. I think a screen top might be too open though, and will let too much humidity/heat out, so I'm going to look at getting a plexiglass top.
Now I have a couple questions.

I picked up an 8.8L bag of Coconut Fibre Bedding, and will be picking up a bag of play sand from Home Depot tonight. Should I combine the 2, or have 1 side sand and 1 side Coconut Fibre?
Should I get another bag of Coconut Fibre Bedding? I didn't get the solid cube stuff, I just got the loose bedding, it's the same thing just not condensed.
I also picked up a large plastic fish bowl, I'm going to lay it on it's side and put some forest moss in it, it will be extra humid and moist.

I also got this All Living Things Coconut Fibre Climbing Background (http://www.petsmart.com/reptile/habitat ... tid-500027) which I think they will enjoy!

I picked up 2 shallow cat food dishes which are going to be their "pools" 1 for salt water and 1 for fresh. I purchased pre-bottled salt water as I wasn't sure how to mix it myself.
I got a couple of pebbles for the bottoms of the pools, 3 of the crabs are fairly large, but there one little guy in there and I don't want him to drown. ALSO, I've seen in several setups that one of the 2 water dishes has a sponge in it, is there a reason for this? The freshwater dish that they came with has a sponge in it but I don't know what it is for.....

They have a coconut hidey house, and I'm going to pick up some climbing sticks/plants tonight while I am out an about. I want to make their home as nice as possible for them
Any suggestions on climbing things that they would like?

One more thing... I'm still completely LOST in regards to heating. I'm planning on ordering an ultratherm, provided they ship to Canada. But what should I use in the meantime?
What size should I get for a 40G tank?
And if I've understood correctly, you're supposed to stick it to the side of the tank?? How is it supposed to make the whole tank warm?
I'm sorry for all the questions, I'm completely new to this and I want to make sure these guys are properly cared for!

[KellyCrabbieLove]

Ultratherms. there are 2 sizes of 40 gal tank. One is a breeder tank that is 36 in long and a long tank that is 48 in long.

If it is a breeder you want to get this one. http://www.reptilebasics.com/ultratherm ... uth-11-x35

If it is a long you want to get this one. http://www.reptilebasics.com/ultratherm ... th-11-x47/

For maximum heat you will want to insulate it with a piece of this. http://m.homedepot.com/p/CelloFoam-3-4- ... 205517302/ Normal duck tape didn't work for me for this. I had to use gorilla tape. I put 2 pieces together to make it extra wide and used it that way.

You can put the heater on a timer if you don't need it on all the time. I maintain my heat and humidity perfectly using an ultra therm and styrofoam with custom glass lids.

You will want to attach the ultrathrm at the top of the back of the tank. We are heating the air, not just the substrate. Do not put it actually under the tank.

[Teedeums]

First of all, congrats on your new little friends!

You can add as much coconut fiber (CF) as you see fit. Most people do a five to one ratio, sand to Eco earth because it is the most natural ratio and it helps keep it moist but not mold. So if you feel like you need another bag of CF, get it. And about the salt water, instant ocean is highly recommended for making it. Some people put a sponge in the dish to help the crabs climb out, but you have to sanitize them a lot, so if you don't want to do that, just chuck it. Crabs seem to love climbing on vines and wood, and sitting on platforms in the air (all can be fake or real). Some also love second levels made from netting. And about heating, if you use a UTH, it is supposed to cover the whole side of the tank above the substrate.

It is really great that you are asking so many questions in regards to their care, they will thank you! Say hi to them for me!

[CallaLily]

I answered in your other thread.