Air bubbles in pump

[Jrea]

Hello,
I'm really no expert in pool but I like to understand how things work. I noticed than when I turn my pump from the skimmer to the suction side (where I plug pool cleaner robot) some air is coming. If it completely turn the lever to the suction side, it looks like only air is coming and a little bit of water. Some videos say that it's because the pump is starving. So I have 2 questions about this :
- If I just turn halfway and some air is coming, does it mean I have a leak ? ( I already replace the o-ring, put shaving all over the pump, and unplugged the robot with the vacuum port open but air bubbles are still there).
- Why the pump is starving on the suction side if the pipe is the same diameter than the skimmer one ?
Thanks a lot for your help

 

[mknauss]

Welcome to the forum.
Your suction side port in the pool should have a cover over it when the hose is not plugged into it. Thus if you try to pull water to the pump at that time, you will be starving the pump.

 

[Jrea]

Welcome to the forum.
Your suction side port in the pool should have a cover over it when the hose is not plugged into it. Thus if you try to pull water to the pump at that time, you will be starving the pump.

Thank you very much for your answer, Indeed, there is a cover but even if I keep it open, the pump is still starving.

 

[mknauss]

That port should only be used when a suction side cleaner is attached.

Normally you must use a mix of suction from the skimmer and the suction side cleaner port to keep the pump from struggling.

 

[1poolman1]

Hello,
I'm really no expert in pool but I like to understand how things work. I noticed than when I turn my pump from the skimmer to the suction side (where I plug pool cleaner robot) some air is coming. If it completely turn the lever to the suction side, it looks like only air is coming and a little bit of water. Some videos say that it's because the pump is starving. So I have 2 questions about this :
- If I just turn halfway and some air is coming, does it mean I have a leak ? ( I already replace the o-ring, put shaving all over the pump, and unplugged the robot with the vacuum port open but air bubbles are still there).
- Why the pump is starving on the suction side if the pipe is the same diameter than the skimmer one ?
Thanks a lot for your help

What horsepower pump is that Whisperflow? Those pumps, especially at higher horsepower ratings, require a lot of water. You have 2" going into the pump, but only 1.5" at the cleaner port in the pool and possibly all the way until it comes out of the ground and is increased to 2".
Also, when you pull from the suction port only you are lifting the water higher, that increases the "low pressure" in the suction side of the pump. Any tiny air leak, and most pools have them after a while, will become a source of air even if it won't leak water.
Check the O rings in the valve, especially the ones on the stem and be sure they are lubed. They are very often overlooked as a source of a suction leak.