i have a pool heater to install the elect lists 208/240-575 vac 60hz 3 phase i have 175 ft from main panel what size sub panel and size wire to feed?

I am going to install a separate sub panel for my pool. currently have a double 60 breaker supplying power to the pool pumps and am not sure if i can upgrade the current feed to accommodate the heater also, so probable just run it separately but not sure the feed size and main breaker size?