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.
To encourage you to put more leafy vegetables on your plate, WebMD asked Nussinow to rank the country's most widely-eaten greens from most nutritious to least. Kale: This nutrition powerhouse offers everything you want in a leafy green, says Nussinow, who gave it her first-place ranking. It's an excellent source of vitamins A C, and K, has a good amount of calcium for a vegetable, and also supplies folate and potassium.