My RODI is not working and SPS coral is dead/dying...is there a connection?

[newreefer_59]

Since December, I have only been in my home about every 2 weeks, and the lady in there now (long story) is caring for the tank with weekly water changes. She was not adding enough salt initially and the SG was at about 1.020, last month. I had her bump up the salt little by little and now it is up to 1.025. In the meantime, almost all of the SPS coral has died or dying and there is purple-ish growth over some area of the tank bottom, as per pic.

Now I notice the RODI TDS meter is displaying water out about 150, when water in is about 170. The water out used to be around 0!! I changed the carbon and sediment filter just now (after 6 months) and the DI filter is scheduled for April. Would the high TDS be killing my SPS coral? All fish seem very healthy. It is a 150 gallon tank with T5 lights, and skimmer seems to be working fine, etc. Any thoughts?