The easy answer -- FLUSH your tanks and lines several times with fresh water.

Are you on well water or chlorinated municipal water at your marina?
If you have chlorinated water, then I'm not sure you need to use the purification method (UNLESS YOUR SYSTEM IS VERY GUNKY). Since it smells a lot, I'm not sure you can avoid that, but (if it were me, I'd) try first NOT TO.

If you want to purify the system, or if you aren't on a municipal water system with chlorine: First, You should NOT put chlorine in a heated how water tank! the next step is to clean your tanks and lines using the purifying instructions that have been posted many times by Peggy Hall on this website (or you can get it from searching on Google. That involves mixing chlorine into FRESH water which is in your tanks, then running that water throughout your plumbing system (hot and cold water), letting it sit for at least 8 hours (But not more than 20 hours, and then FLUSHING THE SYSTEM by replacing all of the brew with FRESH WATER.

If my memory serves, the concentration is 1 cup for each 10 gallons in your fresh water tanks.

Another point, don't put water in your tanks with hoses that have been cooking in the sun with stale water. Flush the hose out well before you stick in your tank fill. Further, use hoses that are designed and rated for potable water. That's not just a green garden hose.