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Originally Posted by Rodger The probe type ph testers that use two dissimilar metals are so inacurate as to be unusable. I've found as much as a difference of +/- ph3 just due to how much moisture is in the sample. |
I just got one of these yesterday. I found my cow manure was 4.5-5ph. I tested it in storebought compost and it read 6.5 as per the packet. In water it is 7. As long as it shows 7 in water and 7 in the casings/substrate it is good enough for me. I hate the digital probes, esp. as they are just for water. I know agar uses a dial one rather than digital too, but it is an really good one.
I would have expected the moisture in the sample to give different readings though. Surely if you add more water the ph will go nearer 7 whether it was higher or lower to begin with?
I added a fair bit of hydrated lime to the manure and left it sit overnight it is now reading 7. Can sodium hydroxide (lye/caustic soda) be used to adjust ph in casings? I heard of somebody using sodium bicarbonate (baking soda) which buffers at about 8.3-8.4