... and I shock my tanks once a year, when I shock the tanks, I will remove the faucet screens so any of the gunk that comes free / out when I shock, stuff in the tanks, but more likely in the lines, won't get trapped in the screens. My tanks are poly, I wouldn't do this for alum or SS tanks, I have a cocktail of bleach and water ... 1 gallon of water and 1/2 cup Clorox bleach solution for every 5 gallons of water ... fill the tanks, remove any screens, run this solution through all the lines, move the boat around, let is all slosh around, agitate, leave it in for at least 3 hours but not longer than 24 hours. During this I will get into each tank and scrub all surfaces. Then I drain each tanks through all the lines completely, fill with fresh water, completely drain, fill again with fresh water & drain. I usually don't have any taste or smell of Clorox after this, but if I do I will run 1 quart of vinegar with 5 gallons of water in the tanks for a few days, that will get rid of any Clorox smell. After that, I don't add any bleach or similar to my tanks during the year.

cheers, John