hygger Aquarium Air Pump,Adjustable Oxygen Pump，Silent Powerful Aerator Pump 2W/3W/4.5W/6W/ 1/2 Air Outlets Ultra for Up to 100 Gallon Tank

https://www.amazon.com.au/dp/B07BHLX1N2/ - should fit nicely in a back corner. https://www.amazon.com.au/hygger-Aquarium-Adjustable-Pump，Silent-Powerful/dp/B0B6W2CK5Y/ - 3w set , this seems like it might be enough without being too much powerful. Or this: https://www.amazon.com.au/hygger-Aqaurium-Silent-Accessories-Aerator/dp/B0FP26XBTL/ Note: these are just examples, you may have to try looking some more yourself. Basic how to set up: https://youtu.be/BS7gIHUkhuo?si=qaRjEMfC5y5yW6Me