What are you guys using to make sure the bottom of your board stays clean and fast!?

We have really hard water down here so oxidation is a problem on boards and boats if not wiped down quick!

I think I read somewhere NOT to use regular wax for some reason, but I want to apply some kind of product...

We have the Broadcast for the boat board and I use a Ronix Koal 5.0. The Koal has a real glossy finish and I want to keep it that way!

Any suggestions!?