Cleaning Soap from Tank

[johnnymax]

So why can't you use old tank water (after a water change)?

Oh, I see what you are getting at ?
Volume is the problem. My tank is only 75 gallons and the tote tank is 275 gallons.
I do a 75% water change once a week. It would take a month of water changes to fill the tank just once.
I am not that patient, LOL