Quartz Glass Submersible Aquarium Heater for Tropical Fish with Suction Cup, Black

i hace 3 of these heaters, one orange light stays on constanly and does not heat the water and one come on and there is alot of bubbles coming from the outside.

works great

I'm using this in a 10 gallon, even though it's a little more power than I need, it doesn't overheat my aquarium one bit. I plan on transferring it to a 20-30 gallon, so hopefully I will have the same success. The red and green lights are both working for me. Do make sure when you set these up that you have the tank filled with water first, then let it run for a day before adding fish, just to make sure there aren't any fluctuations. Sometimes the gauges on these can be off, and that can easily be fixed. It says it works best vertically, but I've had no issues using it horizontally.

I really love this heater, it does a great job at keeping the correct temperature that you set it at. I highly recommend in it if you're looking for a good product.