Tank heater

[Keaton davis]

Was looking at the heater and something seemed to waving off it into the water column. Looks like the street when you can see the hot air moving across the ground. Does anyone know what this means?

 

[JoshO]

Have you checked it hasn't got stuck on or overheating?

 

[homer1475]

It means your heater was on, and heating the water.

 

[CK00020]

That is the heat

 

[Flippers4pups]

Thermal refraction, difference between cooler water and warmer water causing light to refract.