Skimmer air intake not constant

[Aleph]

Hi, I have a Bubble Magus C3 skimmer in a constant level compartment of my sump and sometimes I have trouble with its air intake, it's like it has two levels of intake and every 10 to 15 second it switches, I realize that from two things: the level inside the cup raises and lowers about 4 to 5 cm so I can't properly set the level, and the noise the air intake makes is different.
My first hypothesis was that the intake was clogged so I cleaned the pump and the air tube but nothing has changed.
Second one is that since the skimmer pump is next to the drain tube the flow could interfere with the pump intake, but the change is very regular and periodic so I don't know if that could be the cause.
Third and final, the pump is somehow broken.
So, any thoughts on what could be happening? Thank you!

 

[tsouth]

Is your skimmer still breaking in? Cleaning the pump will increase this break in time, so will cleaning the cup, the body, and so forth. Until it stabilizes itself through continuous running in the tank for a week or so, only then will you be able to really pinpoint its measurements.

Have you tested your second hypothesis by testing it? Move your skimmer to a different chamber with the same water height and test if it works the same or differently. This will rule that in or out right?

My advice - leave it alone, let it run, and leave the skimmer output wide open so that you can understand how it runs and reacts with constants and not variables.

Good luck

 

[Aleph]

Thank you, the skimmer has been running for almost a year now, it has happened previously that I had similar issues but I always thought it was caused by the pump needing to be cleaned because after cleaning it it would return stable. Unfortunately I'm not able to test the second hypothesis because I have a small sump with only one constant level chamber. The only thing that could be correlated is that when I put a filter sock on the drain tube the oscillations seem to be a bit slower but not enough to be proof of anything.
I have been leaving the skimmer untouched for the last three days and unfortunately the issue is always there.

 

[tsouth]

Are there air bubbles coming out of your drain tube?

On another note - have you ever experienced the skimmer *not* fluctuate? If so, what was different then vs now?

Something that may help with clearing the tube instead of having to break it all down - take some R/O water and heat it up til it's hot, but not scolding. Use a turkey baster to fill the venturi silencer and let it all run down the tube.

 

[homer1475]

Look at the venturi(where the airline connect to the skimmer), they sometimes get some calcium precipitate that clogs the venturi causing just what your seeing.

 

[Aleph]

Thanks for the replies!
Well I have experienced that issue before but it wasn't constant, it would do it for a couple hours and then return to normal, it would completely go away after cleaning the pump.
I could have some calcium deposits and have missed them during the cleaning, even though the entire pump was submerged in vinegar for a while but I will try the rodi method you suggested and see what happens...thank you for the help

 

[andrewey]

Where is the outlet for the skimmer (below the water line, above it, etc.). It sounds like you are forming a siphon and breaking that siphon over and over.

 

[Aleph]

This is the skimmer, the outlet should be on the bottom of the regulation tube on the opposite side of the pump

 

[andrewey]

Assuming that riser on the T isn't completely blocked (highly unlikely), then disregard the full siphon idea. How high is the water level in the sump?

 

[Aleph]

It's 19 cm (7.5 inches)