Review on BoxTech Aquarium Heater - 50W/100W/300W Submersible Thermostat with Adjustable Knob, 2 Suction Cups - Suitable for Freshwater and Marine Saltwater Environments - Explosion-Proof by Kayla Miller

The 100w heater is too small for a 30 gallon/10g seawater tank, but I do it on purpose so that it isn't powerful enough when it gets stuck to handle the amount of water to fry there. I'm old school and still use two 150w metal halide bulbs on a 36" display so they provide most of the heat when running, but at night I need something to keep the 80 degrees going. Pros: 1. It's tiny and fits horizontally in my limited skimmer/back section of my sump. 2. I don't need to get wet to adjust it. 3. The power indicator is clearly visible with my other controllers on the outside of the tank 4. Despite its small size, 80 degrees lasts 3-4 swings without it. Cons: Celsius. Maybe perfect for the rest of the world, but here I need my phone to convert to Fahrenheit. One day it will fail, like ALL heaters (the question is when), but so far so good.