How can you advise someone to start the tank again and yet still be asking questions about the cause of the problem?
Dana, it seems to me that there is 'something in the water' or rather a combination of water plus nutrients you are unable to control, rather than anything you are doing wrong.
Before you throw the whole lot out, perhaps consider setting up another tank, or even just a container of water and see what happens so you have something to compare to.... it would be a shame to start all over again and then find the same thing happens.