When laying the base of a swimming pool the pool company must use steel reinforced concrete to ensure it is strong enough to withstand any movement once the pool is finished. The base should be cast in one layer of concrete with the reinforcing grill mid way through the cement. It should not be cast in two layers with the grill dropped on top of the first layer once it had set! It should also have a waterproof membrane underneath which this hasn't. Please check progress with your pool construction as even the big companies are not necessarily doing it correctly.
Chris at Puglia Pools has been maintaining pools in the region for over 9 years after spending 25 years in Customer Service back in the UK. Both Puglia Pools and Perfect Puglia are family run businesses by Chris and Graham with their respective partners Alison and Hayley.