To all dealers out there, we are getting ready to do our first water change. We have never had any issues with our water, been easy to maintain, and get it tested at dealers on a monthly basis. Is it a must to use Swirl Away, or any such product. Would we okay just washing or rinsing tub before adding the new water? Just want to cover all bases. If this has been asked before, please forgive me. Thanks in advance.