Originally posted by newnickname:
I guess it's to do with hydroponics. It seems you need a pump to oxygenate the water that the plants grow in - similar to the set-up in a
fish tank.
'Used with an air stone, air pumps add beneficial oxygen to the nutrient solution of your hydroponics system. By adding oxygen, you’ll encourage a healthy root system and increased growth rates...' bghydro.com('Bubble' is a verb in the phrase you're asking about.)