When you add so much of anything to water you will have residue.
I do not care what it is if it was a xolid there will be somthing left in that tub.
You may want to read up on it, here is one site about the pros and cons of such pools.
A simple thought it could be the salt reacting to the clorine
in the water or other chemicals added to our drinking water
WikiAnswers - What are the advantages and disadvantages of a saltwater swimming pool
Oh yeah the green lines, I think the airplanes that are spraying are droping bar codes on us, LOL1