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.
These veggies have a similar taste and texture, but there are a few minor nutritional differences. Whether you love making salad with baby spinach, or steaming a side of Swiss chard for your grilled chicken, these leafy greens will give you the nutrients you need, without adding a lot of calories to your diet.