Bests & Worsts Reviews from Amazon

I have been using these cheap bi-metal solid electrode pH meters for many years, all the while thinking like many here who gave them glowing reviews that they work as advertised. Over the years I must have bought a small arsenal of these cheap bi-metal electrode meters, ranging from the $10 cheap models, to $20 Rapitest, and to the most pricey $120 Kelway HB-2. Based on my recent experience I can tell you this: save your money and don't bother with these bi-metal solid electrode pH meters no matter who makes them. They are the equivalent of divining rods or dowsing rods. If they seem to work, it's purely by accident and not because of supportable scientific principles. A good clue that these metal electrode pH meters are junk is that their instructions state that they can only be use to measure soil pH but they can't measure pH of liquids. The only soil pH testing methods you can do at home that work are: 1. litmus paper, 2. pH indicator solutions that change color, or 3. very expensive glass electrode or ISFET electrode pH meters. Litmus paper and pH indicator solutions have significant limitations and high uncertainty because the soil can frequently impart a color that can make comparison against the color chart challenging. What prompted me to write this review is that I finally took the plunge after several decades of gardening to buy a very expensive glass electrode pH meter. I did so because a retarded unlicensed concrete "contractor" that my neighbor hired illegally dumped leftover concrete and gallons of highly alkaline concrete wash water onto my very expensive and prized conifers. According to an article on the EPA website concrete wash water has a pH 12, same as a bottle of liquid ammonia cleanser. I am doing everything I can to save my beloved plants and need to know the precise pH with high certainty before I can remediate the soil. The glass electrode pH meter I bought is a Hanna Instruments HI 99121N Direct Soil and Water Portable pH/Temperature Meter ( http://www.amazon.com/Hanna-Instruments-99121N-Portable-Temperature/dp/B003UNK3LU/ref=sr_1_3?s=industrial&ie=UTF8&qid=1432521893&sr=1-3&keywords=hanna+direct+soil+ph+meter ). I did some comparison readings using the Hanna HI-99121N glass electrode pH meter and the Kelway HB-2 bi-metal electrode meter. Here is what I found: 1. Indoor planting mix in a large planter: I took two different readings with the Hanna in two different holes and the pH readings were 5.0 and 5.5. With the Kelway HB-2, the readings were 6.0 and 6.2 respectively. 2. Outdoor soil where the retard concrete guy dumped the concrete wash water: Hanna read 8.0 and 8.2 in two spots. Kelway read 6.2 in the same two spots. The only time the Kelway indicated a high pH reading was when the highly alkaline concrete wash water was freshly dumped onto my yard. I took a reading that very evening with the Kelway and it indicated a pH that was far beyond the top of the scale of pH 8 on the Kelway. How far beyond pH 8 it was I don't know because the Kelway's scale tops out a pH 8. Now two weeks later when the soil has naturally recovered somewhat with a pH 8 (based on the Hanna's reading), the Kelway now reads 6.2. So let me summarize the results: When the soil is highly alkaline (if it is really at let's say pH 12) then the Kelway would indicate a high pH reading. If it is slightly alkaline with a real pH 8 then the Kelway would read 6.2. Do you see a problem here? When the soil is neutral (pH 7) or quite acidic (pH 5 to 5.5), the Kelway would still read 6.0 to 6.2. Do you also see a problem here? You might ask: did I take the readings correctly when using the Kelway? The answer is a definitive Yes. I took precaution to wet the soil with distilled water. I polished the electrodes with the green abrasive sheet and I didn't touch the electrodes with my bare fingers. The needle initially swung to the right (as the instruction stated) when I inserted the electrode into the soil and I waited 2 to 3 minutes before taking the readings. I cleaned the electrode with the abrasive sheet prior to taking each reading. Conclusion: Although my Hanna glass electrode pH meter is very expensive, it is worth every penny to me because it gives the same accuracy that soil labs give. Never again will I waste my time with the metal electrode pH meters. How these manufacturers can keep on selling them to gullible gardeners is beyond comprehension. They get away with it because most gardeners don't know any better and because if these cheap metal electrode pH meters give a reading between 6 and 7 most people automatically think their pH meter is functioning correctly because that's what most people expect their soil pH to be. These metal electrode pH meters are similar to divining rods or dowsing rods. I suppose that if people believe hard enough that they work, they can rationalize (however ridiculously) that they do work. Instead of those bimetal electrode pH meters that don't really work, here are some direct reading soil pH meters that are based on sound scientific principles: Extech PH100 ExStik ($75, available on Amazon), Spectrum FieldScout Soilstik pH meter (about $160, looks almost same as ExStik, but twice the price), Bluelab soil pH pen (about $130) Hanna HI 99121N (about $300). Oakton WD-35634-40 Double Junction pH Spear ($250). ScichemTech pH PEN-5 (about $165, available on Amazon) Lutron model PH-212, Digital Soil pH Meter (about $200) The downside with the above real pH meters is that their electrodes are fragile and the electrodes have to be replaced every few years at big bucks (at 1/3 to 1/2 the cost of the meter) and they require calibration and electrode storage solutions (if the electrodes dry out, they die), but it's still infinitely better than using gardening dowsing rods