Is my Skimmer pumping out too much water?

Hi there guys!

I'm setting up my second marine tank (no fish or coral at the moment) at the moment and just got a question about my protein skimmer.



I have placed my skimmer in the sump but I'm noticing that the skimmer is pumping out A LOT of water through the waste container (half a bucket overnight) and I find it really weird being there are no fish or coral in there at the moment. (note that the water out the skim is murky so i guess it is working..)



I have tried slowing down the skimmer but while that helped it a little, it is only skimming a 45L tank + sump and it seems to be taking out too much water out and I'm worried something is not right.. Is this actually what happens for the first few days?



Any help would be great! Never worked with skimmer (other tank runs off sump alone)