If the circulation system is used correctly, it is by far the most effective method for cleaning most systems. Never re-circulate until you are absolutely certain that the majority of the contaminated solution has been flushed down the drain. After this has been accomplished, refresh your chemical solution and then place return tube into the pick up tank.
While this is taking place, it would be a excellent time to clean the couplers and faucets, check other aspects of system, strengthen relationship with your customer, clean POS, record competitive info, etc., etc., etc.
If you really want to clean up the system, after the alkaline wash and rinse, hit it with an acid wash and rinse.
Scott Zuhse, Instructor
Micro Matic Dispense Institute