Hello. I noticed that when I start the pump and the valve for the main drain is open and the one for the vacuum is close no air bubble get out at all when the pump start. But, if I close the main drain and open the vacuum, leaving only the skimmer and the vacuum on, some air get out from one of my returns and then I get a steady short "stream" of air bubbles that only last for fours seconds or so. Then nothing more. Everything is fine.
Is this is normal? I don't remember having this issue before. The pipes and valves are only one year old. They installed with a new variable speed pump.
In the morning the clear plastic "window" at the pump shows a little bit of air. Not much. After priming it is only water. No air. The filter pressure is steady.
Another question. What are those little "knobs" that you can turn to the right or left located in at the valves? Somewhere here I read that it is to add grease. Should that be tighten to a certain direction?