Cleaning murky water with liquid bleach before draining?

[BigE]

Hi, its time for me to drain my tub, i just bought a chlormaker salt generator.  And now my water is murky with a little mold in the water well.  

Do any of you use bleach to clean the lines before draining?  My tub is 450 gallons.   I read i can add 2 cups of bleach and run for 10 hrs.  

Does this sound right?  I dont want to use any harsh chemicals, like the bottled line cleaners.  

Or...Can i just super shock it with dichlor, let it run for few hrs. and then drain??

[waterbear]

bleach is a better choice than dichlor but you need a purge prodduct like Ahhsome to get rid of biofilm in the plumbing.What makes you think they are 'harsh chemicals'?