Fenix 5 Plus - HRM Swim

Hi All,

I have a Fenix 5 plus and just sourced a HRM Swim - does anyone know if these are actually compatible? 

I am aware how to pair a new device and I am aware the HRM swim records the data in the strap - but how does one make sure the strap is recording and or get the data to the watch after the pool workout? 

Thanks very much in advance