Got hard water? Chances are you’ve also got hazy dishes and a whitish film on your dishwasher innards. For some consumers, these residues have increased since polluting phosphates were banned from dishwasher detergents. And they’ve helped spur the market for detergent additives designed to eliminate hard-water buildup.
We put three such products to the test: Finish Power Up Booster Agent, Glisten Dishwasher Cleaner & Hard Water Spot Remover, and Lemi Shine Original. To ensure the toughest possible conditions, we loaded dishwashers with glassware that was nearly opaque from being washed in extremely hard water (more than 300 total parts per million, or about twice the concentration found in many households). The dishwashers themselves were also hazy with mineral buildup.
When we used the same amount of each product—about 50 grams—all removed the haze from our glassware and cleaned the dishwasher. But if you follow Finish’s directions for machines with a prewash-detergent dispenser, as we did at first, you could be disappointed. If your dispenser holds far less than 50 grams, as ours did, the product won’t work nearly as well. Indeed, even after running a second cycle with the Finish additive, we saw very little improvement. Only the third time, when we placed 2 tablespoons directly into the bottom of the dishwasher (following instructions for machines without a prewash dispenser), did the glassware and dishwasher tub come clean. Glisten and Lemi Shine did their job as directed, though you may need a second wash cycle to eliminate buildup fully.
Bottom line. All three products ultimately proved to be effective, but they may require trial and error depending on your dishwasher and the level of film buildup. That makes price a key factor. At 31 cents per ounce, Lemi Shine offers the best value. Finish costs 40 cents per ounce; Glisten, 87 cents per ounce.
Choosing the right dishwasher detergent could also help. In recent tests, we found that Cascade Complete With Dawn ActionPacs was excellent at resisting mineral buildup while getting dishes and pots clean. And a rinse agent can help eliminate water spots, a less severe condition than white haze. Note that the Finish and Lemi Shine products shouldn’t be used with any dishwasher detergent that contains bleach.