Have you also checked the injector, to make sure its not partially plugged?
I agree there may be a problem with the air intake. Should be able to shut it down. Make sure it has enough plumbing tape on the threads or even a little silicon.
I believe Stephane was driving his Aerofoamer with the 18 and seen dramatic improvement when switched to a Mak4 pump. Dont get me wrong, the 18 will work fine, but I cant see it driving foam all the way up that large skimmer, unless like Clinton mentions, you have a heavy load. Jaysons 36 in. models skimmed well with a Mag 18 on his tanks, but those were 500g stock and grow out tanks.
I would say Clinton level is about perfect to produce good foam, which would be not to wet. The main body itself should be like white pvc with bubbles. My current model is like this, but the 36in. and 32in. models were not, unless I raised the injector to cup level and drove the water level about 2 or 3in. below the cup. This would even be more so with a smaller pump.
You also need to get the airflow right, so as to introduce as much air as possible, but not large bubble. They are to disruptive to the skimmate.
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Doug
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