Electrical resistance heater: consists of a resistance wire wound on earthenware, GE in the glass tube of heat-resistant, waterproof. Wire sealing rubber cover connect the power. Common specifications are 50, 75, 100, 125, 150, 200 watts, can be directly used in the water.
Heater outside the box: now there is a heater outside the box, just like a blanket that Aquarium on heating, electricity. Promotion seems to have improved.
Low voltage heating: this is a more secure method than the heating mode. But need to be equipped with transformer, larger size, placed in a fish bowl, a rough andthey don't look good.