I’m hoping that you may be able to offer some advice Corona 
. We have recently moved house and neither of us have any experience where pools are concerned. Imagine our shock then when we woke yesterday morning to find that the Intex pool had emptied (apart from a few inches near the bottom)! There are no discernable signes of where the leak might be however, over the last week or so, the skimmer has been acting strangely, not sitting at the water level and sounding as though it’s taking in air. This my be a stupid question, but given the speed at which the pool emptied, is it possible that the water could have been sucked out via the skimmer valve? I have attached some photos of the setup. The photo of the valve where a trail of white can be seen on the outside of the pool is the one linked to the skimmer. Sorry for the long post and hope it makes sense.
If it was the skimmer, it would just empty to the lower level of the skimmer. Have you checked all around the low water level for any liner damage?
We did think that but just trying to rule things out. We’ll give the lining another check and failing that will just have to try refilling a bit at a time to see where the leak is coming from. 
Thanks for responding. 
What is the white pipe thats looped over the roller in the first picture? Is it possible that you’ve accidentally siphoned all the water out?
The white pipe is the pool vacuum which was not connected. To use it, you have to disconnect the skimmer hose and attach it to the same outlet.
@mark raised a good point. If that vacuum tube was not closed off at both ends then the pool water could well have emptied it by the siphon effect.
Depending on where you are do just check you are allowed to refill a pool. Some arras are still under restrictions
Hmmm…thank you Brian. That could indeed be a possibility! 
Thank you for the reminder. Will definitely check.
You wouldn’t be alone. I once filled our above-ground pool using a hose from a tap in the barn about 50m away. Once filled, I disconnected the hose at the tap end and left the other end in the pool.
The next morning, I was horrified to find the the barn was flooded. With 25.000 litres of pool water 
Thank God it’s not just us then! 
Thank you Mark for spotting what may be the problem
Blocking one side is sufficient.
You will only get a siphon if water is drawn through the pipe when one end is submerged and the other end is hanging below the level of the water. If the water level gets lower than the level of either of the two pipes, the siphon will stop. So in your case with just a couple oc cms of water left, both ends would have to be within a few cms of the bottom of the pool or lower for it to empty the pool. In @_Brian s case, when he removed the pipe from the tap, the pipe was full of water and dropping it on the floor meant it was well above the level of the water and a syphon drew the water out.
Edit: In your picture, one end of the tube is outside the pool and on the floor, the other going over the side into the pool. If that other end was at the bottom of the pool then that wouldn’t in itself cause a syphon. Something would have had to draw water up the pipe and over the edge to start the syphon.
(Cough) Well below, I believe.
Which is why I referred to the tube being open at both ends.
Now I really am confused . The vacuum head was in the pool after cleaning (may have been water in the white tube which went from the vacuum head, over the side of the pool and onto the floor outside the pool 
That would create the siphon, and nearly empty the pool.
Is the ground wet and boggy? That might give you a clue if it is.
Right, that seems to make sense.