Heater watt for acrylic tank?

[onsloth]

My 300 watts a pretty good on my 140 gallon acrylic. But it doesn't seem efficient for a glass one of 140 gallons.
I'm wondering if a 300watt will be okay for a 180 gallon.
What's the wattage difference needed for acrylic versus glass?

 

[onsloth]

It's crazy to me that this 300 watt heater is keeping this 180 gallon acrylic aquarium tank at 82 degrees Fahrenheit.

 

[Sassafras]

I've never seen a source that quantified the difference, although, being less dense than glass, it is obvious that acrylic would transfer heat less efficiently (be a better insulator). There are other factors, however, that can make an even bigger difference. For example, a tank with an open top vs. one with a cover glass or hood will lose a lot of heat and require more wattage. In tanks with a pump that transfers heat to the water, the pump will do some of the heating work and allow a smaller heater to handle the job. Sumps and HOB filters can make a difference if they create enough water movement/turbulence to increase evaporation, which in turn cools the tank and requires more heat input.