[Myka]

I have no idea what the coconut carbon filter is...???

I may have missed it, but how many GPD is your system rated for? Most RO membranes (Filmtek 50 & 75 gpd and BFS 150 gpd) are 98% efficient which means if the water going in is 100 ppm TDS the water coming out will be 2 ppm TDS when it is new, and that will slowly rise until you need to change it. The Filmtek 100 gpd membranes are only 90% efficient, so if you have the Filmtek 100 gpd this is probably not a good choice for your higher TDS source water. You should be able to replace your flow restrictor with a regular type...they are cheap. Then choose a compatible RO membrane. I would suggest either the 75 gpd or the 150 gpd if you really want, just make sure it is 98% efficient. I think you may have exhausted your DI resins, but you can replace your RO membrane, and figure that out later. Don't forget to replace the sediment and carbon filters before the RO, and flush them before hooking into the RO like described earlier. I would ditch the coconut filter...don't know what's up with that, sounds weird.