If you have an ultratherm, you can try to insulate over your heating pad and tank to raise the temperature of your tank. There are several ways to do this. Don't insulate over your heating pad if it is a zoomed, or any other heating pad that is insulated (padded). If your heating pad is insulated, you would insulate AROUND the heating pad.
Cheaper way: You can use aluminum foil (shiny part facing the crabitat), then cardboard. Attach using packaging tape, duct tape or Reflectix tape.
More expensive: Purchase a product called Reflectix. This product looks like car shade material. It is sold in rolls at local hardware stores like Lowes and Home Depot. You can also purchase it on Amazon. Cut the Reflectix to fit your tank. Attach using packaging tape, duct tape or Reflectix tape.
It can take several hours to see the difference. If doing the insulation doesn't raise your temperature, you might want to consider getting a bigger and or better heater. Most of us use ultratherms. They are great heaters.
www.reptilebasics.com or
www.beanfarm.com sells them.
Hermit crabs have modified gills, and need humidity to breathe. IMO heat lamps are terrible at making the humidity evaporate, so I personally do not like them. A vast majority of crabbers use the ultratherms to heat the air instead of heat lamps.
Humidity boosters: Bubblers definitely do help boost the humidity. Double dish bubblers:
http://hermitcrabassociation.com/phpBB/ ... r#p1030806
You can also add moss pits to help. You would use organic moss (as well as moss that is on the safe list), and moisten it with dechlorinated fresh water. Then, put the moss in a shower caddy or a glass vase laying on it's side so the hermits can walk in and out of it. Glass tops also help keep humidity in.