This pool is losing WATER! Only when the PUMP is on!!

The customer got in contact to carry out a leak detection on their pool. it's losing a lot of water but only when the pump is on. apprently, either the pump off the pool doesn't drop water. we carried out a full investigation and found a large leak. The customer wanted us to block off the pipework and come back it at a later date as they need the pool up and running ASAP. jobs a goodun if you have a leak Let's get it!