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| Just how reliable are these $15 digital pH meters?
I ask because I'm getting some really odd readings out of the one I just bought. The rain barrel? pH 7, exactly what I'd expect. pH of the soil out by the pine trees? About a 5.6, slightly acidic, again about what I'd expect. Tried the leftover potting mix from when I planted my blueberries last year, 5.0, again about what I'd expect from the peat moss/potting soil combo I mixed up. Then I tested the containers with the blueberries themselves, and it read 8.5-9.0, alkaline as freaking baking soda. Wait, what? Mixed some rain water in to a handful of fresh straight up miracle grow potting soil, and it came up as 4.6. Again, what? Since when is standard potting soil the same pH level as acid rain? |
Follow-Up Postings:
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| It has been pretty well decided that they are not worth to much...sorry |
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| Rain water, your tap water (well or municipal) will be something other than 7.0 while distilled water will be 7.0, so if one of these useless, cheap,pH meters is to be used they do need to be cleaned and tested with distilled water first. However, even then a $15.00 will not be very good. |
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- Posted by albert_135 Sunset 2 or 3 (My Page) on Tue, Apr 12, 11 at 15:10
| Back, I'm thinking about 2004-2006, Kimmsr posted a few brilliant paragraphs on pH going into buffer capacity, alkalinity, CEC etc. I think I even complemented Kimmsr in a follow up. The post I am thinking of must have been a copy/paste because I don't recall seeing anything comparable since. The remark about rainwater not having a pH of 7 is correct but not relevant to gardening because rainwater has almost no buffer capacity and the ions causing ''acid rain'' have been largely removed. For the OP I suggest this. Take a container of water, any water as water has near zero buffer capacity. Add some of your blueberry soil to the water and shake it up and let it set for several day shaking occasionally. Test that water with you new pH meter. Is it now closer to what you would want for your blueberrys? |
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