It seems you have started another thread with the same question, unsure why. The pressure side of any pool system runs from pump to return jet, water features, etc. The suction side runs from skimmers, drains and vacuum ports to the pump. With the pump running, the suction side will only suck in air, not leak water. So. if you are losing water when the pump is on, it has to be somewhere from the pump to the returns.

Other than that, you will have to do some troubleshooting or have someone else do it to find the leak, no one here can find the leak for you. Once you find it, let us know if you need any help fixing it.