[slief]

Originally Posted by Pedro3178

Ah! Thank you...

I had a good look and I certainly can’t see any marks or what looked like rubbing of any kind.

I would need to check when I get home but if I remember correct it’s about 3/4 closed to get the level up in the skimmer. The skimmer was purchased January this year.

I am thinking you are going to need to raise your sump level so that the skimmer is in deeper water. Three-quarter closed is way too much. When the load in the system is too low relative to the skimmer size, the skimmer will need to be in deeper water and this is to be expected since this skimmer is pretty well oversized for your current display size. This skimmer is best suited for at least a 100 gallon or 400 liter display with a very heavy load (1/2” of fish per gallon or about 50” of fish) to maintain proper foam fractioning which has a direct impact on the level inside the skimmer. The more waste in the water the less depth needed for the skimmer to maintain a proper level inside the skimmer body without having to restrict the output as much. What’s likely happening is that a siphon is being generated out of the drain side of the skimmer due to the waste pipe been closed so much and restricting the flow out of the skimmer. It can take several hours or more for a siphon to develop but once the surface tension of the water is just right a siphon can form and out the skimmers drain pipe and that will drop the level inside the skimmer down within a couple inches of the level of the drain pipe. I would raise the sump level enough so that you have the wedge pipe no more than half closed. In fact I would raise the sump level to the point where the water level inside the skimmer is up to about 2 inches below the white part that the collection cup sits on with the wedge pipe wide open. That would be your driest skim setting and you would only have to close the wedge pipe fraction to adjust the skim wetter. My guess is that you will need to raise the level in the sump several CM’s so that you can raise the level up to that point while the wedge is wide open.