Mapleleaf, this post is 4 years old but you are correct, no bleach. That post should have read 1/2 cup baking soda mixed with 1/2 cup of salt followed with a cup of vinegar.

What is the "sump" area?

Hi Mapleleaf and Welcome to The Plumbing Page. At AskMeHelpDesk.com. You're responding to a 5 year old dead thread so I gave you one of your own. Look in then upper left hand corner of the first post form the date before you post, Thanks,

What is the "sump" area?
You'll find the sump at the lowest point of the tub. This is the basin that contains the water that drains back from the hose after the pump shuts off. Just follow the directions given by Bob and you'll be just fine. Good luck, Tom