pond pump?
so you’ve taken @QGA’s suggestion and you’re gonna use the SPD for goldfish?
I think that was anything larger than 5L 
look for something designed to move hot water.
cheap: solar water circulator https://www.walmart.com/ip/Moaere-DC-12V-24V-700L-H-Submersible-Thermoplastic-Utility-Water-Pump-with-Cable-Length-79-for-Fish-Tank-Pond-Aquarium/465350317
slightly more expensive: household hot water circulator Robot or human?
those are examples not recommendations.
I’d recommend spending a little more, and getting one in stainless…but I tend to like gear that I can re-purpose later, and a decent hot water pump has a number of uses.
edit: about the same time as your first pass. give or take.
Edit: my favorite hot water pump is the Bosch pump that Mercedes use to circulate coolant through the heater core. They run for 30+ years in the engine compartment, passing fluid at 115C. I of course source them used for $10 or less