Because it is a junk, that is why. This skimmer does not work and needs constant adjustment. It is a waste of money IMHO!!
新缸是打不出東西的, 所以不用緊張!
So you are saying that the synthetic sea salt does not contain any major or minor trace elements?? The water is so pure that it does not contain any wastes?? Mind you of the tank cycling process???
It does not matter if a tank is new or not, a skimmer once adjusted correctly, will work no matter what is the length of the tank. This skimmer is a piece of junk, that is why nothing is foaming.