Troubleshooting Skimmer Overflowing

[nerdymunky]

I have a RO 150int Skimmer that I’ve been running off and on for about 3 years (moving across states ain’t no picnic). I just recently set up a new tank to upgrade my current nano to a 75 gal cube with this Skimmer below in a DIY 40b sump.

It had been running fine until I started to add more live rock into the display, when the Skimmer started to overflow with foamy water out the top. I assumed it was some particulates from the rock getting sucked into the Skimmer, so I took it apart, thoroughly cleaned it and put it back in. Odd thing is... the Skimmer doesn’t overflow if the air line is disconnected. I’ve verified no restrictions or particles in the air line, so I am at a loss to where my issue is at. Even the return pipe’s restriction gate valve is opened completely.

Anyone seen this or can offer advice? My next step is to try a vinegar bath.

 

[nautical_nathaniel]

Is it not producing enough bubbles or something? The pump motor may be going bad in it and not spinning fast enough to cavitate the needle wheel impeller with incoming air.

 

[nerdymunky]

Is it not producing enough bubbles or something? The pump motor may be going bad in it and not spinning fast enough to cavitate the needle wheel impeller with incoming air.

It’s acting like the return valve is completely closed, so it goes up the neck and overflows the cup in about 30 seconds.

 

[nautical_nathaniel]

It’s acting like the return valve is completely closed, so it goes up the neck and overflows the cup in about 30 seconds.

I'd do the vinegar bath like you were thinking about doing and see if that frees up any components from salt creep or calcium buildup and such.

 

[nerdymunky]

I'd do the vinegar bath like you were thinking about doing and see if that frees up any components from salt creep or calcium buildup and such.

That’s the idea, though it already looks squeaky clean when I just took it apart to look for some obvious debris.

 

[nerdymunky]

Vinegar bath proved the only part dirty was the collection cup.

Tore everything apart and rinsed it with rodi. 10 seconds after plugging it back in:

This time, I even raised my Skimmer to be in 7” of water rather than the 8-ish it was in.

For kicks, I plugged in an Aquatrance 1000s from a HOB Skimmer and got the same frustrating results.... just slower. What am I overlooking?

Is it really a bad pump, even with a smaller pump giving the same results?