HCA: Hermit Crab Association

Well, I just got them. And I was using a basking light But just realized my infrared heat lamp. What I been using for night was what I just needed for all round temp. So I was cleaning my tank. And noticed the water was cold.

I'm having trouble getting my water warm, and to stay warm. I'm very knew and doing a ton of research. But cant seem what to do about the water. It keeps getting cold