Tunze 9012 DC - Excessive Amount of Bubbles


New member
I purchased a brand new Tunze 9012 DC about a month ago, and it has been running on my new tank for 3 weeks now. I was reading that I need to give the skimmer time to break in, but after 3 weeks, I'm seeing no sign of the amount of bubbles reducing.
The skimmer is dialed so that it is fully open, and I have elevated the skimmer so that the intake is barely above the water line. Anything lower than that and the amount of bubbles leaking from the skimmer makes my back chamber of my AIO look like a bubble bath.
The skimmer is skimming very wet. Hardly any sludge being collected on the sides of the cup. I'm basically just getting grey water in the collection cup.
I read that sometimes the bubbles are coming from the seals and that I have to make sure that the skimmer body is assembled firmly, but that is not the issue here. The bubbles look like they're coming from the back of the skimmer. As I have an AIO, it is very difficult for me to see where exactly. Here are some photos of the skimmer in action and the back of the skimmer.



Source of bubbles from back (since this is in an AIO chamber, I can not tell if the bubbles are coming from the bottom)
<a href="https://imgur.com/khkxuvw"><img src="https://i.imgur.com/khkxuvw.jpg" title="source: imgur.com" /></a>

Bubbles coming out to the front:
<a href="https://imgur.com/F3Aa1c1"><img src="https://i.imgur.com/F3Aa1c1.jpg" title="source: imgur.com" /></a>

Skimmer back
<a href="https://imgur.com/ckuCXw4"><img src="https://i.imgur.com/ckuCXw4.jpg" title="source: imgur.com" /></a>


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The intake under the cup should not be submerged more than half way, generally the depth is correct when no bubbles escape the front, from what I see, with bubbles escaping the intake, it is too deep. In general with the DC model the pump will never be turned up to more than about 40%. A DC pump at half power is equal to the AC pump with the air all the way opened. I would raise the skimmer and turn the pump down all the way and slowly increase it as needed. Be careful that the cup is properly seated, it has two clear tabs that must seat inside the black housing.