The number one way to clean out your tank--
& be assured all microbes & bacteria are purged,
is to flush with a solution of Clorox.
It doesn't take much; any bottle of the stuff gives proper
amounts to add per gallon of water.

Third world travelers know that even bad drinking water
can be purified with Clorox, tho it's not the preferred method.
Just be certain to flush the tank afterward to remove the odor.

Sure, Bicorbonate of Soda will "freshen" the tank,
just as it absorbs odors when a box of it is placed
in a refrigerator, but it will *not kill bacteria.

Salud!
Phaedra