These are the ones.
4 of them does the trick.
View attachment 315679
The key to succes is to use a pond airport with a capacity of 1800liter/hour
The common Aquarium airpump are no good for this purpose
I regulate the excess air bij blowing this off with a bypass controlled with valve.
It just set and forget.
If more skimming is required i just close the valve a little bit tigther.
Sorry to muck up your thread. You've always said to talk with you here.
I got myself a new toy today. I've always loved air stone skimmers as I'm the type that likes to tinker. I've built several but I decided to purchase this one.
It's 8" diameter. An alita 25m to drive it and a maxi jet 1200 for a feed pump. Not sure of the stone but he says its a lifetime stone. Just clean and reuse. I may try wood stones for fun at some point.