My situation is this. I have an RO system with a DI filter as well. My water comes out with zero tds. I have 3 containers two with straight up RO in which there is not a problem. The third contains salt water in which are 2 heaters, and no light. I noticed a presence of brown slime covering the inside of this plastic container. I do not know where to start dealing with this issue. Please advise #reefsquad