getting that hard look while on water

Dear Dr Joe& Team I am one of the few that still keep water on contest day I look full but never hard on contest day just read the article on peaking I drink two gallons of water a day and carb load sun-tues how can I add potassium& sodium to achieve that hard look forgot to mention I am a over the road truckerdriver, contest weigh is 155lbs hope you can help me I have 7wks before next show