Skimmers have what is called a break in period.
Can you adjust the flow in or out to raise the level in the skimmer?
If so you need to ;
a; slow it down on way out
b; increase the flow into skimmer
Make adjsutments slowly as some skimmers re act slowly to adjustment.
That's a coralife skimmer ? I
Those red nobs on the outlet is how you adjust the level. I had that exact skimmer and hated it. The worst part was how hard the collection cup was to get off. I would invest in a skimmer with a variable DC driver that makes adjusting it so easy. I'm not trying to talk bad about your skimmer. I just wanted to share my experience. Those red nobs are so hard to get right.
This looks identical to my Aquatop setup by the way.
In sump skimmer or HOB? Kind of looks in sump. If it is in sump there are multiple ways of controlling them (ie controlling the water flow coming in from the return pump via the valve that is generally on them, the knobs there. Be aware that skimmers are super touchy and as mentioned have a break in period in which they can fluctuate with their results (ie going from skimming all kinds of stuff to skimming nothing). It likely just needs an adjustment.