https://store.koenderswatersolutions.com/search?q=Airstone+diffuser
I originally purchased the 20’ koenders windmill kit and just continued to use the diffuser that came with it. I really don’t have any other experience with aeration so I would not be able to say much more about diffusers. It creates about a 4 ft circle of various size bubble with the hiblow and the minnows love it. I’m a beekeeper so I just tried to use resources that I have. I had purchased an ANEL 10 frame plastic beehive with the screened bottom and later on decided to get away from 10 frame equipment because it gets really heavy. So I repurposed.