Cleansing fresh water tank

[Double Horizon]

After a year or more, the fresh water tank and hoses will start to grow certain organisms and it is a good idea to "shock" the system with chlorine once per year for Spring commissioning. Here's what I did to clean my DF-1200 tank.

1) Remove the screen from the water pressure pump, and replace the normal pressure output water hose with a short (2-3 ft) 1/2" ID hose to run the water into the engine bilge. (Alternatively a longer section of hose could be run directly overboard).
2) Empty the tank by turning on the fresh water pressure pump.
3) Remove the tank level sender and look in with a flashlight -- you will likely see "growth" particles in the remaining water.
4) Suction out the remaining water and "growth" particles with a shop vacuum (to fit inside the sender hole, I used duct-tape to adapt a 3-ft. 1-1/4" OD plastic hose to my shop vacuum hose)
5) Refill tank and repeat until you can't see any more particles floating around in the tank.
6) Replace filter screen on the pressure pump, and then reconnect your normal output hose. Confirm your water works again.
7) Pour 16 oz. (2 cups) of Clorox (laundry) Bleach into the water tank, which is the right amount for 35 gallons capacity. Replace the water level sender.
8) Fill tank. Run water through each faucet until you smell the strong chlorine smell. Let the chlorine sit in the tank and water lines for 8 - 12 hours but not longer than 24 hours (it's corrosive). That will kill everything that grows.
9) Run all the chlorinated water out and refill tank with fresh water, then run out the lines again to get rid of the chlorine in the lines.