I do not believe any zeolites or potassium will help you keep blue corals. I have intense blue corals and I do not use either. I do believe that keeping perfect water conditions will help, and I do think lighting is critical. Most corals having blue in them need intense light and can be enhanced with light that tends towards the blue spectrum. So . . . if you want blue corals I suggest keeping your water parameters as close to an Indonesian reef as possible and investing in high intensity blue spectrum lights using either Radium MH bulbs, T5 actinics, or blue LEDs as a primary light source.
But then that is only one man's opinion so I hope you will take everyone's advice and come up with the best answer for you!
Joe