Hi there, welcome to the forum!!
I just installed a skimmer that uses a "block" as well for air. Is the airstone producing the same amount of bubbles as the old one did? I know a mod is suggested with some of these skimmers that you add two stones for more bubbles. But I don't know what kind of skimmer you have.
Do you have a picture?
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.