Hydroponic and Organic Gardening

When is Your Water Too Dirty?

Let’s look at a possible scenario. Say you test your water and learn that the ppm is 300 and the hardness (calcium and magnesium) is 11 grains or 188 ppm (1 grain of hardness is equal to 17.1 ppm hardness).

Because you’re on well water you surmise the other 112 ppm are other minerals, such as iron, and possibly sulphur. The water tastes great to you and your friends and everyone believes it would be great water to garden with. It’s time to transplant some freshly rooted cuttings into larger containers. You know you are working with a variety of flowers that are sensitive to high ppm in their early stages. You want to keep your feed formula at around 400 ppm for the first week. At this point do you add 400 ppm of food to your water that is already 300 ppm or do you only add 100 ppm food? That’s the dilemma — you can never accurately control the amounts of critical inputs your plants need to feed properly.
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Most growers have ppm pens or monitors that can tell them the quality of their water. This is a good starting point, but knowing the hardness (calcium and magnesium) of the water is important, to see how much of the ppm is the hardness and how much is other contaminants. There is a myriad of other substances that can be read by a ppm pen. Sources for ppm in your water include agricultural runoff, urban runoff, industrial waste water, sewage, and natural sources such as leaves, silt, plankton, and rocks. Piping or plumbing may also release metals into the water and add to the ppm.

Below is a guide to identifying certain water problems:
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