Yesterday, I bought a Hagen Thermal Compact submersible heater (25 Watt) for a small tank. It has a knob to adjust the temperature. I thought that it was probably the type that you just twist to adjust, but it seems really difficult to turn (its covered by rubber which twists around the knob when you try to turn). If any of you have one please let me know how to properly adjust it. I haven't tried very hard to adjust it because I am afraid that I might break it. The instructions that came with it didn't really help.
Also, do you know if is it safe to place this heater in an arylic tank? Right now I'm using it in a glass tank.
Also, do you know if is it safe to place this heater in an arylic tank? Right now I'm using it in a glass tank.