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  1. #1

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    Default pH / EC / TDS / PPM

    What are the pros and cons of buying a combo meter?

    The combination type meters are real handy for the convenience of being able to take both readings simultaneously, or with a single touch of a button to switch between modes. The problem IMHO with combination meters is pH sensors like to be stored in a fertilizer solution, but TDS probes like to be stored in distilled water. Storing the pH probe in plain or distilled water will damage the ph membrane, so the combination probe needs to be stored in a fertilizer solution so as not to damage the pH portion, so the TDS probe ends up being "dirty" from salt buildup. A friend has already lost one expensive probe on his Hanna from this same problem, and will only purchase "single function" pH or TDS meters in the future.

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    Arrow What is the difference between ppm and EC?

    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.

    EC is measured in millisiemens per centimeter (ms/cm) or microsiemens per centimeter (us/cm).

    One millisiemen = 1000 microsiemens.

    EC and CF (Conductivity Factor) are easily converted between each other.
    1 ms/cm = 10 CF

    "The communication problem"...
    So again, the problem is that different ppm pen manufacturers use different conversion factors to calculate the ppm they display. All ppm (TDS, Total Dissolved Solids) pens actually measure in EC or CF and run a conversion program to display the reading in ppm's.

    There are three conversion factors which various manufacturers use for displaying ppm's...

    USA 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
    European 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
    Australian 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

    For example,

    Hanna, Milwaukee 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
    Eutech 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
    Truncheon 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

    Calculating the conversion factor

    If your meter allows you to switch between EC and TDS units, your conversion factor can be easily determined by dividing one by the other.

    Place the probe in the solution and read TDS in ppm. Change to EC on the meter and read EC in ms/cm.

    Conversion factor = ppm / ec.

    [Note: ms must be converted to us: One millisiemen = 1000 microsiemens (1.0 ms/cm = 1000.0 us/cm)

    According to the chart below:
    1.0 ms/cm = 500 ppm (USA Hanna)
    1000 us/cm = 500 ppm

    Conversion factor = ppm / (ms/cm * 1000)
    .50 = 500ppm / (1000us/cm) ]

    The answer is your meter's convertion factor and should be a number between 0.50 and 0.72 To improve accuracy, take ec and ppm readings from your res daily for about ten days. Average the conversion factors. The more data points that you use, the closer you will be to finding your true conversion factor.

    When reporting your PPM in a thread, please give the conversion factor your meter uses. For example: 550 PPM @0.7 or give the reading in EC, which should be the same meter to meter.

    It may also be advisable to give the starting value of your water; there is a huge difference between RO and distilled water with a PPM of approximately 0 and hard tap water of PPM 300 @.5 (notice the conversion factor so others can work out the EC) or well water with a conductance of 2.1 ms/cm.


    A note to Organic Growers:
    An EC meter has fewer applications for a soil grower because many organic nutrients are not electrically charged or are inert. Things like Superthrive or Fish Emulsion, blood meal, rock phosphate or green sand cannot be measured with a meter reliably when they are applied or in runoff. Meters can only measure electrically charged salts in solution.

    "The solution"...
    When reporting your PPM in a thread please give the conversion factor your meter uses for example 550 PPM @.7 or give the reading in EC (the EC shoul d be the same meter to meter).


    EC Hanna Eutech Truncheon CF
    ms/cm 0.5 ppm 0.64 ppm 0.70 ppm 0
    0.1 50 ppm 64 ppm 70 ppm 1
    0.2 100 ppm 128 ppm 140 ppm 2
    0.3 150 ppm 192 ppm 210 ppm 3
    0.4 200 ppm 256 ppm 280 ppm 4
    0.5 250 ppm 320 ppm 350 ppm 5
    0.6 300 ppm 384 ppm 420 ppm 6
    0.7 350 ppm 448 ppm 490 ppm 7
    0.8 400 ppm 512 ppm 560 ppm 8
    0.9 450 ppm 576 ppm 630 ppm 9
    1.0 500 ppm 640 ppm 700 ppm 10
    1.1 550 ppm 704 ppm 770 ppm 11
    1.2 600 ppm 768 ppm 840 ppm 12
    1.3 650 ppm 832 ppm 910 ppm 13
    1.4 700 ppm 896 ppm 980 ppm 14
    1.5 750 ppm 960 ppm 1050 ppm 15
    1.6 800 ppm 1024 ppm 1120 ppm 16
    1.7 850 ppm 1088 ppm 1190 ppm 17
    1.8 900 ppm 1152 ppm 1260 ppm 18
    1.9 950 ppm 1216 ppm 1330 ppm 19
    2.0 1000 ppm 1280 ppm 1400 ppm 20
    2.1 1050 ppm 1334 ppm 1470 ppm 21
    2.2 1100 ppm 1408 ppm 1540 ppm 22
    2.3 1150 ppm 1472 ppm 1610 ppm 23
    2.4 1200 ppm 1536 ppm 1680 ppm 24
    2.5 1250 ppm 1600 ppm 1750 ppm 25
    2.6 1300 ppm 1664 ppm 1820 ppm 26
    2.7 1350 ppm 1728 ppm 1890 ppm 27
    2.8 1400 ppm 1792 ppm 1960 ppm 28
    2.9 1450 ppm 1856 ppm 2030 ppm 29
    3.0 1500 ppm 1920 ppm 2100 ppm 30
    3.1 1550 ppm 1984 ppm 2170 ppm 31
    3.2 1600 ppm 2048 ppm 2240 ppm 32

  3. #3

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    Thumbs up How do I tell if my PPM/EC is too high or too low?

    It's simple to find out if you are using too much food or not enough by watching the nutrient concentration levels in your tanks day to day. Don't be concerned with the exact reading, rather watch how it rises and falls from each day to the next. The differences between when you put the solution into the tank and the readings you get several hours later or the next day are what tell you if your plant is eating, drinking or happy.

    Start with 1.00 EC (or a SAFE nutrient strength). Next day, if it reads 1.4, it means your plants have been using water and your nutrient solution is becoming more concentrated. This means the concentration of nutrients is too high, so you dilute.

    If the meter reads lower than the previous day, 0.7 say, it tells you that the plants are eating nutrients faster than they are drinking water, so you should increase your nutrient strength. If it remains the same, your feeding schedule is on target for now. The nutrient/water intake fluctuates with the growth of the plant, so you must continually monitor it day to day.

    Your plants will tell you the optimum nutrient levels. When they are receiving optimum food and water, the readings remain constant. The more you do it, the easier it gets. The reason no one can tell you what PPM/EC levels to use is because every garden is different and every plant has different requirements due to their particular environment. That's why you have a ball park starting figure, but after that your plants will tell you almost exactly what they require.

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    Thumbs up What is a good ph/EC/TDS meter?

    Added by: MisterIto

    I use and recommend the Hanna HI9813 Grocheck portable ph, ppm and EC meter. It is available from most larger indoor garden supply retailers for around $200. I have had one for several years and it never drifts more than .2 on the ph scale or 30ppm from the original calibration made. I keep the electrode immersed in Hanna storage solution and use a hand held trigger sprayer to clean the film and residue that accumulates on it. I feel this contributes to my consistent readings without any need for re-calibration at all.

    Added by ~shabang~:

    I've had the lower model waterproof Oakton pens for over 5 years with no problems. I've replaced the pH probe twice since I let it dry out too long, but I did that for piece of mind and not because it really needed it.

  5. #5

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    Default What is a good ph/EC/TDS meter?

    You can find some great meters here .

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    Wink How can I raise or lower the pH of my soil mix?

    How can I raise or lower the pH of my soil mix?

    Growing in soil and adjusting pH levels

    A lot of gardeners have trouble with the pH of their soil. A high pH can lock out needed nutrients and mimic other problems like Fe and Mg deficiencies. The biggest mistake new growers make is to try and correct pH problems too quickly. The first step in determining if high pH is the real problem, is to pick up a good pH tester. Don't be afraid to shell out the cash for a good one, it's well worth it!

    Here are some recommendations: (All sell for under $100.00)

    1. Milwaukee makes two styles of hand-held pH meters. A small "pen" called the Sharp and the larger Smart Meter. Both are easy to use. The Sharp pens are splash-proof (although not totally waterproof), and have a large easy to read display. They also have a detachable, replaceable probe.

    2. Oakton - Same type of pH tester as Milwaukee makes, but it's made a little better imho. These are totally waterproof. (It floats.)

    3. Shindengen ISFET pH Meters are state-of-the-art pH pens and work with a totally different method of measurement. This pen uses a solid state Ion Sensitive Field Effect Transistor (ISFET) instead of the fragile glass electrodes used by traditional pH pens. They have replaceable tips that change from opaque to clear when they need to be changed.


    What is pH, and what do the terms acidic and alkaline mean?
    The acidity or alkalinity of the soil is measured by pH (potential Hydrogen ions). Basically it's a measure of the amount of lime (calcium) contained in your soil, and the type of soil that you have. A soil with a pH lower than 7.0 is an acidic soil and one with a pH higher than 7.0 is considered to be alkaline. A pH of 7.0 is neutral.


    Adjusting your soil pH :
    Once you have determined the pH of your soil with a good tester, you can amend the soil if needed to accommodate the plants in your garden using inexpensive materials commonly available at your local garden center.


    Adjust soil pH slowly over several days time, and check pH often as you go. Radical changes in pH may cause osmotic shock damage to the roots.

    Raising soil pH : (to make it more alkaline)
    It is generally easier to make soil mixes more alkaline than it is to make them more acidic. The addition of dolomite lime, hardwood ash, bone meal, crushed marble, or crushed oyster shells will help to raise the soil pH.

    by MisterIto
    In soil: add dolomite limestone to the soil; use small amounts of hydrated lime.

    Raising hydroponic pH : (to make it more alkaline)

    In hydroponics: use potassium silicate, provides silicon at an effective doseage.
    In bioponics/hydro-organics: add small amounts of sodium bicarbonate or lime.

    Lowering soil pH : (to make it more acidic)
    If your soil needs to be more acidic, sawdust, composted leaves, wood chips, cottonseed meal, leaf mold and especially peat moss, will lower the soil pH.

    by MisterIto
    bloodmeal/cottonseed meal during vegetative; bonemeal during flowering.

    Lowering hydroponic pH : (to make it more acidic)

    In hydroponics: use nitric acid during vegetative; phosphoric acid during flowering.

    Contributed by: Spiritual.Fa
    23-08-2003

    Stabilizing pH with Dolomite lime

    The best way to stable PH is by adding 1 ounce of Dolomite Lime per 1 gallon of planting soil.

    Dolomite Lime is available in garden nurseries. Buy the fine Dolomite powder (There may be several kinds of Dolomite like Rough, Medium, Fine)

    Dolomite Lime has been a useful PH stabilizer for years, since it has a neutral PH of 7 when added to your soil it stabilizes your soil at PH 7.

    Mix the dry soil medium and dolomite together really well, give the mix a good watering then after the water has had chance to settle and leech into the soil a bit give the mix a really good stir. Then water the soil/lime mix and give it another stir

    Best plan is to mix fine dolomite lime into your mix before planting. Fine Dolomite will help stabilize your pH; however, if the ph becomes unstable or changes, you can then use Hydrated Dolomite Lime. Add some of the hydrated lime to luke warm water and give it a good stir then water your plants with it. Give the plants a good watering with this hydrated lime added and your PH should fall or rise back to 7

    Other Benefits of Dolomite Lime

    Dolomite lime is also high in two secondary nutes that can often be overlooked by fertilizers; dolomite is high in both (Mg) Magnesium and (Ca) Calcium.

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    Default

    thanks for info really came in helpful love it took me a year to find that out sad i know but thanks, i use a bluelab truncheon i brought on shere fact it cost the most, as i see you know abit about these nutrient testers could you tell me if this bluelab one is any good thanks ?

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    Default

    Quote Originally Posted by lkdj2003 View Post
    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.

    EC is measured in millisiemens per centimeter (ms/cm) or microsiemens per centimeter (us/cm).

    One millisiemen = 1000 microsiemens.

    EC and CF (Conductivity Factor) are easily converted between each other.
    1 ms/cm = 10 CF

    "The communication problem"...
    So again, the problem is that different ppm pen manufacturers use different conversion factors to calculate the ppm they display. All ppm (TDS, Total Dissolved Solids) pens actually measure in EC or CF and run a conversion program to display the reading in ppm's.

    There are three conversion factors which various manufacturers use for displaying ppm's...

    USA 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
    European 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
    Australian 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

    For example,

    Hanna, Milwaukee 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
    Eutech 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
    Truncheon 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

    Calculating the conversion factor

    If your meter allows you to switch between EC and TDS units, your conversion factor can be easily determined by dividing one by the other.

    Place the probe in the solution and read TDS in ppm. Change to EC on the meter and read EC in ms/cm.

    Conversion factor = ppm / ec.

    [Note: ms must be converted to us: One millisiemen = 1000 microsiemens (1.0 ms/cm = 1000.0 us/cm)

    According to the chart below:
    1.0 ms/cm = 500 ppm (USA Hanna)
    1000 us/cm = 500 ppm

    Conversion factor = ppm / (ms/cm * 1000)
    .50 = 500ppm / (1000us/cm) ]

    The answer is your meter's convertion factor and should be a number between 0.50 and 0.72 To improve accuracy, take ec and ppm readings from your res daily for about ten days. Average the conversion factors. The more data points that you use, the closer you will be to finding your true conversion factor.

    When reporting your PPM in a thread, please give the conversion factor your meter uses. For example: 550 PPM @0.7 or give the reading in EC, which should be the same meter to meter.

    It may also be advisable to give the starting value of your water; there is a huge difference between RO and distilled water with a PPM of approximately 0 and hard tap water of PPM 300 @.5 (notice the conversion factor so others can work out the EC) or well water with a conductance of 2.1 ms/cm.


    A note to Organic Growers:
    An EC meter has fewer applications for a soil grower because many organic nutrients are not electrically charged or are inert. Things like Superthrive or Fish Emulsion, blood meal, rock phosphate or green sand cannot be measured with a meter reliably when they are applied or in runoff. Meters can only measure electrically charged salts in solution.

    "The solution"...
    When reporting your PPM in a thread please give the conversion factor your meter uses for example 550 PPM @.7 or give the reading in EC (the EC shoul d be the same meter to meter).


    EC Hanna Eutech Truncheon CF
    ms/cm 0.5 ppm 0.64 ppm 0.70 ppm 0
    0.1 50 ppm 64 ppm 70 ppm 1
    0.2 100 ppm 128 ppm 140 ppm 2
    0.3 150 ppm 192 ppm 210 ppm 3
    0.4 200 ppm 256 ppm 280 ppm 4
    0.5 250 ppm 320 ppm 350 ppm 5
    0.6 300 ppm 384 ppm 420 ppm 6
    0.7 350 ppm 448 ppm 490 ppm 7
    0.8 400 ppm 512 ppm 560 ppm 8
    0.9 450 ppm 576 ppm 630 ppm 9
    1.0 500 ppm 640 ppm 700 ppm 10
    1.1 550 ppm 704 ppm 770 ppm 11
    1.2 600 ppm 768 ppm 840 ppm 12
    1.3 650 ppm 832 ppm 910 ppm 13
    1.4 700 ppm 896 ppm 980 ppm 14
    1.5 750 ppm 960 ppm 1050 ppm 15
    1.6 800 ppm 1024 ppm 1120 ppm 16
    1.7 850 ppm 1088 ppm 1190 ppm 17
    1.8 900 ppm 1152 ppm 1260 ppm 18
    1.9 950 ppm 1216 ppm 1330 ppm 19
    2.0 1000 ppm 1280 ppm 1400 ppm 20
    2.1 1050 ppm 1334 ppm 1470 ppm 21
    2.2 1100 ppm 1408 ppm 1540 ppm 22
    2.3 1150 ppm 1472 ppm 1610 ppm 23
    2.4 1200 ppm 1536 ppm 1680 ppm 24
    2.5 1250 ppm 1600 ppm 1750 ppm 25
    2.6 1300 ppm 1664 ppm 1820 ppm 26
    2.7 1350 ppm 1728 ppm 1890 ppm 27
    2.8 1400 ppm 1792 ppm 1960 ppm 28
    2.9 1450 ppm 1856 ppm 2030 ppm 29
    3.0 1500 ppm 1920 ppm 2100 ppm 30
    3.1 1550 ppm 1984 ppm 2170 ppm 31
    3.2 1600 ppm 2048 ppm 2240 ppm 32
    You're always on point, Mogie. Basically they all end up giving you he info you need in PPM...

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  11. #9

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    thanks for all the info on meters and krap ive soil grown b4 but hydro is relitivly new to me
    and i was having trouble figuring out what meters to buy but this thread has help immensly this is a truly wonderfl site
    thanx again >chronic

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    Ebay have some good cheap TDS/PPM meters,i got mn for £15 and its pretty acurate to.
    Plant a Seed
    ........&........
    Free the Weed

    https://www.thctalk.com/gallery/showg.../500/ppuser/11

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