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| trial of two prong probe, Soil Master
blueberry patch that has had pine needles and Holly-Tone with sulfur put on for years - between 6 and 7. lawn that has been limed, between 4.5 and 5.5. Tap water, 6 Vinegar added, acid, goes down to 4, okay. water with a few drops of bleach, alkaline, 4 water, spoon of baking soda, alkaline, 4 Second trial, Rapitest, 1 prong
Why on earth do these probes give acid readings for alkaline substances? The second probe wouldn't return to 6 for tap water either, would only go up to 5 or 5.5. What is a good product to test at home, or do I have to send to a lab? I would rather test at home since I am aiming at different pH levels in different gardens. |
Follow-Up Postings:
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- Posted by toxcrusadr (My Page) on Thu, May 31, 12 at 18:20
| Hmm, it appears your meters are not working properly, OR they need better rinsing or a chance to equilibrate. You didn't say what you did to clean them between readings. I would suggest rinsing with distilled or deionized water, then placing in a clean container of the same until neutral reading is observed before moving to the next sample. BTW, bleach is neither acid nor alkaline, it is an oxidizer but not an acid or base. It is a rather reactive and harsh chemical. I don't know how your probes are constructed but I noticed that (if the sequence was as you listed them) things went south after the bleach... |
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- Posted by toxcrusadr (My Page) on Thu, May 31, 12 at 18:22
| Did either of these come with calibration instructions or solutions to use? Baking soda is a good one, a half teaspoon in a cup of deionized water should be about 8.3. Vinegar is also a good one for the acid end, about 4 as you stated, maybe 4.5, again diluted in water. |
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- Posted by birdgardner NJ/ 6b (My Page) on Thu, May 31, 12 at 22:55
| I used the baking soda before bleach. And the bleach was very dilute, only a couple drops in a glass of water. |
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- Posted by blazeaglory 10 SZ22 OC Ca (My Page) on Thu, May 31, 12 at 23:44
| I had my tap water tested by my city and it is 7.7. I use that as a base for my testing. When I put the meter in a glass of tap water I leave it for a couple minutes as It moves SLOW. I know my meter is off by ONE point so I adjust my readings. Just make sure you test something that you already know the EXACT Ph of and you can gauge how well your meter works. Also be sure to leave your meter in its testing site for a few minutes to get an accurate reading. Nothing short of an industrial tester or lab analysis will give you exact results but prong testers will suffice for the home. I just use a paper towel with rubbing alcohol to clean and rinse with water between uses. |
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| Distilled water should have a pH of 7.0 and that is used to set most pH meters, "zero" them in. If you get the same reading in Vinegar as you do in bleach there is a fatal problem with that meter. I have not seen any that cost less than several hundred dollars that were any good. |
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- Posted by toxcrusadr (My Page) on Fri, Jun 1, 12 at 15:05
| A good meter will have two adjustments used at different points. One sets the meter at the first point (4 for example), the second sets the slope so it reads correctly at the second point (8 for example). I don't know what those consumer grade meters have. |
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