HCA: Hermit Crab Association

I recently upgraded to a twenty gallon tank. Humidity at 80% is great. I bought Fluker's corner bowls that hold 6-8 ounces of water. The fresh water is fine, but the salt water evaporates by the time I get home from work or overnight. I removed the sea sponge, thinking that might be soaking it up. No change. Any ideas? Do I need to go back to plastic?

I have not had to refill the fresh water in a week. Only two small to medium size hermies in this large tank, so typically 4 oz of saltwater lasts a few days.

Two thoughts come to mind: Are you certain that your humidity guage is accurate, and how close is the saltwater to your heating?

Going with jclee, where is your saltwater bowl situated in relation to your heater(s)? Most likely it's evaporating with it's right next to it.

However there's two pressing matters that I want to bring to light:
- Sea sponge. There's no need for a sea sponge, especially in the water bowls. All they do is harbour bacteria and pretty much make a mess of things. Best bet is to throw it out or just offer it as a snack for the crabs to nibble on (like a cuttlefish bone). Plus they hardly raise the tank humidity; unless you have a sponge the size of a baseball!
- Weekly FW changes. Try to up the water change schedule to every 2nd night, preferably every night. The 4oz pools aren't big enough to sustain a beneficial bacteria colony. In such a small water source, things can get nasty quickly. Adding/replacing the water with *fresh* water helps us stay on top of the nasties plus the crabs do deserve (IMO) access to clean water. (Not to mention that crabs love clean water)

I would check the dish for leaks. Or if the dish is partially buried in the substrate or if your crabs push substrate up beside the dish a lot, water could be wicking out that way.

If it's the Flukers bowls I'm thinking of, they hold around an inch of water, if that. I use them in my scorpion tanks since they're too shallow for the hermits, and there are many days when they'll dry out overnight in winter when it's dry from the furnace.

Thanks everyone! The saltwater is on the heated side of the tank so I will switch the bowls and see if the fresh starts drying up. Then check for leaks if that doesn't work. Thanks for the info on sea sponges. I thought they were necessary. Thanks for the advice!