Ok when you turn off the skimmer, water backflows into the venturi tubing. So when you restart the skimmer, you have to blow that water back out. I dont know if this is a problem with all skimmers but I haven't heard anyone say they had this issue with other brands. It makes it annoying to use with a controller, for instance, if you like to turn off the skimmer for feedings. I also have a hard time adjusting it but that could be because I'm using it as a gravity fed recirculating skimmer. The instructions that come with it are useless so you have to figure it out on your own. Mine also seems to always have small leaks so I get salt creep everywhere but I run it externally ( to save the save in the sump ) and have it sitting in a tub.
If you put a valve on the output side of the skimmer it makes it tons easier to adjust. Originally mine kept overflowing and being inconsistent because it is gravity fed until i put the valve in. since then i havent adjusted it once and it skims great.