Printable View
I'm mixed up on this whole subject of water/nutes! Is there a clear explanation of PPM , EC , TDS readings, and what to look for to make those adjustments to the water/nutes? Also I need a meter to read all this, where can I find a meter under $70.00 to gain my readings????????:rasta:
Hi Silver,
Well TDS is short for "Total Dissolved Solids" which is read in Parts per million = PPM. EC is just a different way of checking TDS each meter comes with instructions. You can get a Sharp TDS meter for around $80 and then just get the calibration solution to go with it. Just do a web search for "Sharp TDS meter's for sale" and you'll find lots of place to get one.
Herbus
LOL what really kils me is that these 3 terms all have to do with one another so closely - like PPM can be appilied to your CO2 levels AND nuet level. same too with EC
EC can both help you with nuets and water PH
TDS relates to both and tells you how high or low your levels are ....confirm?
what i need to see is all the stats on paper to understand what it takes to run a soild program
From the overgrow FAQ.. hope it doesn't confuse you more:
Total Dissolved Solids (TDS) is the best measurement of the nutrient concentration of a hydroponic solution. To estimate TDS, one can use a meter that measures the Electric Conductivity (EC) of a solution, and convert the number to TDS in parts per million (ppm). Many meters will do this conversion. Total dissolved solids (TDS) is typically expressed in parts per million (ppm). It is a measurement of mass and determined by weighing, called a gravimetric analysis. A solution of nutrients dissolved in water at a strength of 700 ppm means that there are 700 milligrams if dissolved solids present for every liter of water. To accurately calculate total dissolved solids (TDS), one would evaporate a measured filtered sample to dryness, and weigh the residue. This type of measurement requires accurate liquid measurement, glassware, a drying oven, and a milligram balance. Example: 50 mL of the 700ppm solution would leave 35 mg of salt at the bottom of a crucible after drying. Electrical Conductivity (EC) is expressed in siemens per centimeter (s/cm) or milliseimens per centimeter(ms/cm). It can be determined with an inexpensive hand held meter. Nutrient ions have an electrical charge, a whole number, usually a positive or negative 1, 2, or 3. EC is a measurement of all those charges in the solution that conduct electricity. The greater the quantity of nutrient ions in a solution, the more electricity that will be conducted by that solution. A material has a conductance of one siemens if one ampere of electric current can pass through it per volt of electric potential. It is the reciprocal of the ohm, the standard unit of electrical resistance. A siemens is also called a mho (ohm backwards). For convenience, EC measurements often are converted to TDS units (ppm) by the meter. The meter cannot directly measure TDS as described above, and instead uses a linear conversion factor to calculate it. Everyone’s nutrient mix is different, so no factor will be exact. The meter uses an approximate conversion factor, because the exact composition of the mix is not known. Conversion factors range from .50 to .72, *depending on the meter manufacturer, which do a good job of approximating a TDS calculation from the meter’s measurement of EC. * All ppm pens actually measure the value based on EC and then convert the EC value to display the ppm value, having different conversion factors between differing manufacturers is why we have this problem communicating nutrient measurments between one another.
thank you sir