Kelway PHD Soil PH Meter (Pack of 3)

This soil pH meter is wildly inaccurate. If you are trying to adjust your soil pH based on this meter, you will be led completely astray. I researched this meter before buying it, and as a result purchased a pack of the "conditioning films" and a calibration solution test kit from Atlas Scientific with the same order. I read all instructions and followed them precisely. I even used separate conditioning films on each of the two metal rings to insure there was no metallic cross-contamination between the rings. When reading the meter, I interpolated between the 0.2pH scale markings to make readings with a "resolution" of 0.05pH.First test: When placed in the 4.0pH calibration solution, the Kelway meter read 5.20pH. Hunh.The Kelway instructions state, "Use when the soil is damp. No current can flow in soil that is very dry." and "Press the soil tightly against the metal rings." Clearly, the Kelway meter is not intended to be used in fluid samples. I thought perhaps the meter would not work accurately in a completely fluid solution.So, I took a large soil sample and "homogenized" it as thoroughly as possible. I placed a measured amount of this sample in each of three clean glasses. To sample A, I added a measured amount of distilled water. To make sample B acidic, I added an equal measured amount of the 4.0pH calibration solution. I then mixed a solution of powdered dolomite limestone and distilled water. To make sample C alkaline, I added an equal measured amount of this solution. I then measured all three samples with the Kelway meter, taking readings on 1 minute intervals. A subset of the readings taken in this second test is shown below:1 min: A - 6.40pH, B - 6.30pH, C - 6.60pH.3 min: A - 6.50pH, B - 6.50pH, C - 6.70pH.6 min: A - 6.60pH, B - 6.60pH, C - 6.75pH.These readings left me with no confidence in the accuracy of the Kelway meter, so I ordered a Rozway Digital pH Meter. This meter is provided with packets of powder that allow you to mix calibration solutions of 4.01pH, 6.86pH and 9.18pH. The instructions call for the use of deionized water in these solutions. I had only distilled water available, which is not the same thing, so my calibration of the Rozway meter may not have been fully accurate.When placed in the Atlas Scientific 4.0pH calibration solution, the Rozway meter read 3.86pH. Hunh. Not the specified +/-0.01pH accuracy.I then mixed the three Rozway calibration solutions and performed the calibration procedure. After calibration, the three solutions read: 4.01pH, 6.91pH and 9.04pH. Two of these readings are outside the specified accuracy of +/-0.01pH, but that may be my fault due to the use of distilled water. After calibration, the Atlas Scientific 4.0pH test solution read 3.91pH. I then tested the three Rozway solutions with the Kelway meter and measured 5.10pH, 5.15pH and 5.40pH.The instructions for the Rozway meter speak of "immersing the electrode into the solution". Obviously, the Rozway meter is not expected to work with soil that is merely damp, as is specified for the Kelway meter. So I added two more measured quantities of the specified fluids to each of the soil samples described above. This turned them into slurries. I made measurements in this third test by stirring the slurries and inserting the meters (I tested both, individually) before the solids settled out.The Rozway meter read: A - 6.82pH, B - 5.95pH, C - 7.32pH.The Kelway meter read: 1 min: A - 7.00pH, B - 6.60pH, C - 7.05pH.In truth, I had expected a wider range of pH readings among the three samples. However, I do have confidence that the Rozway meter readings are accurate to perhaps +/-0.1pH. At best, I would place the accuracy of the Kelway meter at +/-1.5pH. Clearly, the readings obtained from the Kelway meter are more dependent upon the "fluidity" of the sample and the "settling time" allowed, than they are on the true pH of the soil sample. The pH of soil sample A should not have changed between the second test (one measured quantity of distilled water) and the third test (three measured quantities of distilled water). Yet the Kelway reading changed from 6.40pH to 7.00pH. In the second test, the Kelway reading for sample A changed from 6.40pH at 1 minute to 6.50pH at 3 minutes to 6.60pH at 6 minutes. The pH of the three soil samples (Rozway readings) was: A - 6.82pH, B - 5.95pH, C - 7.32pH, a span of 1.37pH. The pH measured by the Kelway meter (3 minutes, second test) was: A - 6.50pH, B - 6.50pH, C - 6.70pH, a span of 0.20pH. The pH measured by the Kelway meter (1 minute, third test) was: A - 7.00pH, B - 6.60pH, C - 7.05pH, a span of 0.45pH. To re-state my conclusion: the readings obtained from the Kelway meter clearly are more dependent upon the "fluidity" of the sample and the "settling time" allowed, than they are on the true pH of the soil sample. I have absolutely ZERO confidence in the accuracy of readings made with the Kelway meter.

No label "made is Japan" as on picture. I assumed those are not made in Japan anymore...5 years ago I had a good experience with this PH testes, but now it's just expensive peace of junk...The first PH tested doesn't work at all see the collaboration reading below...OK, maybe I got unlucky and I ordered replacement... It came 2 days letter and reading was better but still way off: For 4.01 I am getting 6.0 after 5 min waiting as instructed... I am returning both of them.. DON'T buy this PHI am getting better result with cheaper 11$ PH reader....On picture: on the left : replacement item, on the right : original...Reference solution: 250 ml distilled water at 25C + reference 4.01PHFirst picture reading 30 seconds..Second picture reading after 5 minutes...Testing original PH device with:Distilled water : 7.0 as expected.Distilled water + 4.1 PH reference solutions (250ml) 25C -> 6.5 (Expecting 4.1PH)Distilled water + 6.9 PH reference solutions (250ml) 25C -> 6.9 (Expecting 6.9PH)Distilled water + backing soda, expected to be alkaline around 7.0PH -> 6.5Conclusion: doesn't work at all'Returning...

We started raising blueberries. They and several other plants we grow, such as hollies, need a fairly accurate pH. This is a clever design, using the acid in the soil to make a small electric current which is converted by the unit into the pH reading. It is easy to keep the bi-metallic point clean. (Putting two dissimilar metals in an acid produces electricity.) The reading takes only a few seconds to finalize. Be advised that the reading will not be accurate until the soil has warmed up in the spring. Also the soil must have some moisture in it to produce the reading. This meter is not designed to work in alkaline soils.

This thing is easy to use very accurate, tried cheaper ph meter was only 1.5 ph off it read 7 kelway read 5.5dialed ph in plants are green and healthy now.Spend the bucks and get a excellent ph meter and stop thinking the cheap ones work good.I would still be trying to get my plants green and healthy if I hadn't purchased the kelway

I think this one works, BUT I did have to dampen the test area with distilled water to make the gage move. Someone mentioned that it says that in the instructions. It does, but the instructions make it seem as if you only need to do that if the soil is bone dry ("Use when the soil is damp. No current can flow in soil that is very dry."). The gage only moved when I thoroughly dampened the test area. I then got a reading of 5.5 on my blueberries - just about what I expected.

Nice instrument. My initial impressions were quite positive. After cleaning the probe surfaces per the instructions (a very simple task), I tested my soil in several (about 20) different locations. I am planting acid-loving plants (blueberries), so I had previously conditioned the soil to bring the soil pH to within 4.5-5.5. This meter showed me which areas needed further treatment, and which areas were good to go. The meter settled on a reading quickly and remained stable until I removed the probe and wiped it down to prepare for the next reading. It turns out that my untreated soil averaged between 6.0 and 6.5. My conditioned areas were mostly right where I needed to be -- around 4.8. It remains to be seen how this instrument will hold up, but I expect it to provide years of service. Stay tuned.

I have tried several of those $15 soil tester machines but they all register 7. I spent a bit more by buying this one but it was worth it! I planted some blueberries last year and acidified the soil and this did a great job; at various spots I got samples ranging from 4 to 6. Then when I moved it to my lawn I got 7.Bottom line is if you want an accurate PH tester, this is it!