If that ever happened to me, I would go ape s**t on the stupid *** for not knowing their job. And I am not the cleaner of the fish tank we have, hubby is. And for all the posts I have read here, I know that there will always be NITRATES in a fish tank. So do what everybody said to do and take back the readings or do them yourself and show the stupids and say what everyone else said. Or go above their heads and call whomever you have to (District Manager, Corporate Office) and be VERY VERY VERY assertive. And you dont have to take no for an answer..And they say customers ALWAYS right:mad2: :mad2: :mad2: