Hey Nabbig, I read the title here, and had to stop in and see what you need.
I have 15 hermit crabs, (14 purple pinchers, 1 Ecuadorian) in a 75 tall AQ. Their sub is a mix of playsand, and Eco Earth. Some like to molt in the EE, some prefer the play sand, but I mixed the whole mess, since the crabs do it anyways.
A great place for hermit crab info, and around the clock, hermit crab support is
www.landhermitcrabs.com, I would suggest going to the ZOEA board first, and reading the articles at the top of the forum.
Purple pinchers LIKE having 2 dishes of water, each deep enough to go to the eyestalks of the largest crab. 1 with dechlorinated fresh water, the other with dechlorinated salt water. Now use Aquarium-grade marine tank salt for this. As heavy metals will kill your hermies.
All of the other hermit crab species NEED a dish of saltwater, Strawberries need it saltier than others though.
When I started out, I had the typical petstore recommended conditions, calci-sand, commercial food, painted shells, and only fresh water. But I noticed my hermies were much happier/healthier, when I put moist playsand in there (sandcastle consistancy) and a bowl of saltwater.
I feed my crabs "Southern Greens" which is collards, mustard, and watercress, and comes pre-mixed in a bag at Meijer, for $2.50 I also put in Mango, and pirckly pear fruit, but I grate it, since the food is shared with my igs, and they're still small. My hermit crabs love their food, and I've never seen better colors on them!! I also offer freeze dried gammarus, and bloodworms, this way they won't attack any molters for much-needed Chiton.
Check out that website I posted, and I can guarentee your crabs will thank you!!
BTW, if you need anything else feel free to PM me!!