[porthole]

1 3/4 to 2 cups of bleach for the 100 gallon tank.

Method 1
Pour the bleach into the hose, hook up water, fill tank.

Method 2
I use a sump pump in a 5 gallon bucket, water and bleach and pump into the fresh water drain tube using a slip on Sharkbite fitting.and appropriate adapters for the pump.

Once above is done run cold water faucets till you can smell the bleach then lit sit 8-10 hours then flush.