I have a 2018 Bass Tracker PT 175 TXW and it has a bilge pump, but it is not automatic. Does anyone have any ideas on weather to buy an automatic switch or just buy and install an automatic bilge pump? 

This is a personal preference thing.  To me, a switch is easy enough to wire into your existing circuitry. Its just a wire from the + side of the battery to the switch then to the positive lead on the pump wiring.  Switching out bilge pumps may be more time consuming assuming it is mounted and plumbed in a place where access may be difficult.

 

Just add a float switch