1 In general, the total dissolved solids concentration is the sum of the cations (positively charged) and anions (negatively charged) ions in the water. 2  Parts per Million (ppm) is the weight-to-weight ratio of any ion to water.  A TDS meter is based on the electrical conductivity (EC) of water.
Collard greens may be worth considering for health additions to your diet. These dark-green leafy vegetables provide iron, vitamin K, folate, calcium and the antioxidants lutein and zeaxanthin. They may even help you prevent gout or reduce your symptoms when you eat collard greens in moderation as part of a healthy diet.
Like kale, collard greens contain only 1 gram of fat and 30 micrograms of sodium. With 9 grams of carbohydrates and 4 grams of protein, collard greens contain slightly more of these nutrients than either kale or Swiss chard. Of the three types of greens, collards offer the highest amount of fiber, with 5 grams per cup.