Pump losing prime but only when vacuuming

The pump primes fine under normal conditions and when back-washing, but when I vacuum it loses prime in about 1-2 minutes. If I turn off the pump and wait 15 seconds and turn it back on, it primes fine again for a few minutes. The vacuuming hose is attached at the skimmer. Could this be an air leak in the hose?

Thanks,
C

An air leak in the hose is what it sounds like to me.

Thank you for your reply, I'll try replacing the hose and see how it pans out.

Thanks,
C