Ph & Ec Meter

Is the yield of your plants not as large as expected? Do your plants often display "burnt" symptoms of overfertilization? The solution might be to start using pH and EC meters.

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1. Why Use pH and EC Meters? A pH meter measures the acidity of the water on a scale from zero to 14. This scale is not a linear scale, but an exponential scale. This means that the difference between a pH of six and a pH of seven is gigantic. When the pH is too high or too low, the roots cannot take up the nutrients in the proper proportions. Generally, this will show up in the plant as deficiencies of one nutrient or another, and as burnt leaf tips, caused by overfertilization of one nutrient. The result is that growth will slow, the yield will be low, and ultimately, the plant may die. One remedy is to give the plants fewer nutrients, but then they are certain to develop even more deficiencies, and the yield will not be as good as it can be. When the pH is just right, it is unlikely that deficiencies will occur. The plant will be able to take up the nutrients in the correct proportions and overfertilization will be a thing of the past. In other words: with the wrong pH, half the recommended nutrients will cause overfertilization. With the right pH, the full recommended dose will make for healthy and strong plants. An EC meter measures the electrical conductivity of the water. Clean water has a low EC. When you add nutrients and pH adjusters, the EC will go up. You can use this for measuring how many nutrients can put in the water without causing overfertilization. It can be hard sometimes to eyeball the required amount of nutrients. Sometimes, you're not quite sure how big your container water is or you have no means of measuring the nutrients accurately. Even if all these things are no problem, it is still possible that the recommended dosage of nutrients as printed on the label is too low for your plants, and your plants would benefit from a higher dose. Using an EC meter together with a pH meter, you can measure the optimum dose for your plants without causing overfertilization.

2. How To Use pH and EC Meters Growing in soil The pH should be 6.4 when you sprout the seeds or plant the clones. As the weeks go by, slowly lower the pH until it is 6.0 during the last month of flowering. This will allow the plants to take up fewer nutrients when they are little and more nutrients when they are growing and flowering. Similarly, the EC should be 1.0 when you sprout the seeds or plant the clones. Slowly raise the EC to 2.0 for the last four weeks of flowering.

3. General Tips The pH can be lowered by using vinegar, or you can buy special pH Down from the bigger garden supply stores. These stores will also sell pH Up. Adjusting the pH can be maddening sometimes, because the scale is exponential. In practical terms, this means that you have to lower the pH or raise the pH by adding very small amounts of adjusters. If your pH is too high, and you add too much pH Down, you have to add pH Up. This can go on for while, and then your EC might be too high. Recalibrate the pH and EC meters about once a month. Some meters need a special storage solution for the sensor. Please be sure to buy this storage solution as well, it will make the difference between a well-working meter and a useless meter. Do not use the EC meter without also measuring and adjusting the pH. If you use the EC meter only, you almost certainly kill your plants by overfertilization. You can, however, use a pH meter without an EC meter as long as you don't add more nutrients than recommended on the label of the nutrients bottle. Recommendations for using pH and EC meters with hydroponics will be added later. •

Features Specifications: pH Meter, pH Tester, EC Meter

Features (pH meter):1) Range of measurement: 0.0 - 14.02) Range of measuring error: ±0.13) Gradations: 0.14) Temperature compensation: 5 - 50oC5) Working termperature: 0 - 50oCFeatures (EC meter):1) Range of measurement: 10 - 1990us/cm2) Accurac

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Why is there a need for temperature compensation in pH measurements?

1. The Solution Temperature Effect When temperature changes, the actual pH of the solution being measured changes. This change is not an error caused by the change in temperature. It is the true pH of the solution at the new temperature. Since this is not an error, there is no need to correct or compensate for this temperature effect. To be absolutely correct, document both the pH and temperature of the sample.

2. The pH Electrode Temperature Effect There is only one major temperature effect in pH measurement that can cause errors in readings. This is the change in the electrode's response (or sensitivity) to pH that results from a change in temperature. It is the only reasonably predictable error due to changes in temperature, and is the only temperature related factor that pH meters with temperature compensation can correct. This temperature error is very close to 0.003 pH/oC/pH unit away from pH7. In a perfect pH electrode - one that is zeroed at exactly pH 7 - there is no temperature effect on the electrode sensitivity at pH 7 no matter how much the temperature changes. Most pH electrodes are not perfect, but the errors from changes in temperature are still very minute when near pH 7, plus or

minus one-tenths of a pH, and can be disregarded. However, the further from pH 7 the solution is and the greater the temperature changes, the greater the measurement error due to changes in the electrode's sensitivity. These errors from changes in electrode sensitivity due to changes in temperature can be corrected by meters with temperature compensation.

There are two variations for temperature compensation: Automatic: when a meter is able to automatically correct the pH reading for changes in electrode sensitivity by means of a temperature sensor at the tip of a pH electrode.

Manual: where the user must set or enter the solution temperature by means of push buttons or a dial. The meter then corrects the pH readings for changes in the electrode sensitivity. Temperature compensation eliminates most of the temperature dependent measurement error from the electrode. Further minimization of this error in both temperature compensating and nontemperature compensating pH meters can be made by calibrating the instrument and electrode in pH buffers that are close to the expected measurement values for pH and at (or near) the same temperature as the solution to be measured. This technique also minimizes other temperature related errors which occur in all electrodes but which cannot be predicted or compensated for when temperature changes. These unpredictable pH measurement errors due to temperature changes are somewhat complex in nature and vary from electrode to electrode. They can result in small but noticeable pH measurement errors. Unfortunately, there is not much that can be done about these in a manner that is economical or practical for most users of pH instruments. Therefore as a practical matter, they are mostly ignored in everyday pH applications.