Tunze 9002 skimmate?

[KH971]

I have had other skimmers before and got out of reef tanks for 4 years and I have started back with a JBJ 28 gal tank.
I purchased the 9002 new and also purchased the Slim fit cup for it. The tank has an ATO system and salinity is 1.025.
It did produce some nice foam after it broke in for a couple of hours then, it filled the collection cup with water.
I emptied the cup and it will not produce foam anymore? I have adjusted height and did an airline mod with an adjustable air valve. I can micro adjust my air now. I have double checked the skimmer pump output, the air output, all is good and correct. All I am getting is a buildup of big bubbles, no foam.
The venture outlet is properly aligned, the only thing I can think is where the output of the pump goes up into the slight hump of in the inside of the skimmer, the bubbles are joining and forming larger bubbles. I wondered why there might not be a slight slope up into the neck of the skimmer so the bubbles would not have time to form larger bubbles? It is the only thing that I can think that is happening. Any ideas?

 

[rvitko]

The hump is supposed to be their, the bubbles and water bounce off and diffuse and they all have this.

The airline mod will generally reduce how much air it gets, it is a longer line and the pump has to work harder to pull in the air and they also tend to kink. It will generally still work as the pump has power to spare but a sharp drop in performance will usually point to a kink in the hose.

It may also be too deeply submerged, the marked line should be regarded as the maximum.

Larger bubbles are usually related to water chemistry. Some additives and filter medias affect the formation and stability of the bubbles. Fatty foods can also cause this. This will generally resolve itself after 3-7 days of discontinuing the additive or cutting back on the fatty foods.