In most cases, the OptiPure QTI or FXI series water filter systems with the patented IsoNet scale inhibiting technology will provide the best protection. However, if you have very high Total Dissolved Solids (TDS) or high sodium, chlorides or sulfates, it might be desirable to go with our OP or BWS Reverse Osmosis (RO) systems to lower the TDS, providing a very high-quality ice. If you notice that your ice is soft and melts quickly, then it is likely due to high TDS. An OP or BWS RO system may be the best solution to provide you with a solid, long-lasting ice cube.