What are you using for Electrolyte replacement during and post ride?

FYI - I am doing a low carb diet and have lost 50 pounds since February. I must admit that I have gone sideways the last month and need to get back on track but, I have kept the weight off (I ride 150 miles a week and exercise at the YMCA).

At my age I have no desire to be a racer so, longer rides at a slower pace are just fine with me.