I set up my air lines using I think it was 20mm clear hose which was running off LP100 or larger air pumps.
Hose hooked onto pump with radiator clamp and using black polly 90 deg bends or ends which were secured using zip ties rather then the black polly clips, I thought less air would escape.
Used 4mm irrigation barbs pushed into the plastic hose and they gave a good seal also, there are 2 types of barbs , one with a sharp ends and one with just push points. Used a pair of pointy nose pliers to get the barbs through the hose.
Used standard 4mm air line just pushed onto the barbs and then airlines into sponge filters and used airline control valves .
If interested I have attached a photo of airline fittings I would sell and there are more around I would top up the box.