Best way to unblock intake pipe?

[Miki]

I believe my vacuum may have sucked up 1-2 rocks that my nephew has dropped into the pool. My husband and I have taken apart the hose to check if they were in there, but to no avail.
The vacuum still "works" on full suction, but when the pump is turned off, it kicks the hose out from the intake port on the pool wall.
What are some good ways to unblock this pipe from the pump side? Or would anyone have any idea if it could be caused by another problem?
Thanks very much!

[dynamictiger]

This is more indicative of air not being purged completely from your filter on start up. I am assuming your filter pump is the vacuum pump and it is not a seperate system.

What happens is when the pump starts up, any air in the system goes into the filter. A small hole in the MPV normally bleeds the air from the high pressure to low pressure side of the valve resulting in bubbles in the pool. This small hole commonly blocks resulting in the air being trapped. As long as the pump runs this is where the air remains. However, upon stopping the air decompresses pushing the water backwards through the pump, and in your case pushing the hose out from the wall.

You could get the MPV taken apart and unblock the hole. However, the simplest fix is to fit a non return valve between the pump and filter. This will prevent the air blowing back toward the pump and consequently the hose out of the wall.

HTH