DrTentgrow
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Hello I've got a cheap soil pH meter and was wandering how accurate they are?
Cheap soil pH meter how accurate are they?
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DrTentgrow
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DrTentgrow
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The one i have doesn't have batteries or any means of calibration.
that tester is HORRIBLE!!! Throw it away or return it now! I got one just for giggles, and did a test, it said 8.0ph for a cup of water, I then proceeded to add enough "ph down" to kill anything living and it went down to 7.5
Get a chemical test, its cheap, and it does the job fine
Get a chemical test, its cheap, and it does the job fine
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DrTentgrow
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Why were you using it for liquids? it's made for soil Ive got a expensive electronic one for measuring my water/nutrient solution i will be investing in a decent soil one for my next grow.
the best way to test your soil ph is so easy, I don't know why so many people have problems getting a correct reading.
All you have to do is fill a sealable container that can hold 100mls of liqued! Now get 50ml of soil from within your pot from about two to three inches beneath the surface without disturbing the roots and add it and 100ml of distiled water to your container, put the lid on shake it.
Let it sit for a few mins till the water turns clear now test the water with an electronic ph pen and you'll have a better idea of what your soil ph is with out spending lots of £££
All you have to do is fill a sealable container that can hold 100mls of liqued! Now get 50ml of soil from within your pot from about two to three inches beneath the surface without disturbing the roots and add it and 100ml of distiled water to your container, put the lid on shake it.
Let it sit for a few mins till the water turns clear now test the water with an electronic ph pen and you'll have a better idea of what your soil ph is with out spending lots of £££
Giantsfan24
New Member
I know this is a WAY old post but I've never seen this method of testing soil ph anywhere before...does anyone have experience with testing soil this way?
Giantsfan24
New Member
Actually I did a little research in other places and did find this method out there. That said, it seems like the ph of the water would totally screw with the results and seems like it would be far less than accurate..
Thanks!
Exactly!
As always: pH is NOT a linear thing, its exponential. So pH measuring needs quite tight conditions to be at least a wee bit accurate.
In the lab we use an exact ammount of soil, which has to be dried for an exact ammount of time, then solved in an exact ammount of a specific solvent (KCl), then has to be shaked an exact ammount of time, filtered and then tested with an exactly calibrated pH Meter.
If you loose any data (like the ammount of solvent) before you finish or screw up one of those steps (like letting it solve for a minute too long) the results are absolutely worthless. And Iam just talking about an accuracy of 2 fractional digits.
Once I forgot to soak the filter-paper in the KCl solvent before the filtering and the original pH of the paper screwed my results beyond the rainbow.
As always: pH is NOT a linear thing, its exponential. So pH measuring needs quite tight conditions to be at least a wee bit accurate.
In the lab we use an exact ammount of soil, which has to be dried for an exact ammount of time, then solved in an exact ammount of a specific solvent (KCl), then has to be shaked an exact ammount of time, filtered and then tested with an exactly calibrated pH Meter.
If you loose any data (like the ammount of solvent) before you finish or screw up one of those steps (like letting it solve for a minute too long) the results are absolutely worthless. And Iam just talking about an accuracy of 2 fractional digits.
Once I forgot to soak the filter-paper in the KCl solvent before the filtering and the original pH of the paper screwed my results beyond the rainbow.
Giantsfan24
New Member
So given the extreme variables, what is one left with for the best possible ph results? Ensuring that the water is ph right and you have soil that has been ph tested to specific parameters and is ready out of the bag?
It seems like if you get the right soil then be ultra anal about your water, the rest will take care of itself...but I could be and am willing to be wrong! LOL
Is it even necessary to test the run off water if these two variables are taken into account upfront?
runoff, runoff, runoff. check the friggin soil ph by checking runoff. get your runoff right and your soil will be right, end of discussion. 
The runoff can be very roughly used to see if there is any major change in the soils´ pH but it will not give you an accurate idea of the soils´own pH. The problem with soil is that it has a so called "acid buffer capacity". On Hydro, the runn off water is way more ecact as the hydro mediums do not buffer the pH.
Best thing is: Get decent soil with its pH printed on the bag and use a good pH tester/meter for your water and everything is ok.
Best thing is: Get decent soil with its pH printed on the bag and use a good pH tester/meter for your water and everything is ok.
100ml if liquid? Would a can of beer do?
Tap water? Distilled water?
Even those need to be ph'd before you can obtain an accurate reading. Now where does this leave us? Back to how reliable are cheap digital meters?
As to your quote:
Intelligence will most likely be the catalyst for evolutionary naturally selected towards extinction. Enjoy while we can!
lolool...luv seeing old threads brought to life...cheap PH meters are not worth the meager investment...IMHO...especially the triple function meters(light, moisture, PH)...personally I prefer test strips or powdered reagents...no calibration required...butt...that's just me...cheerz...h00k...
lolool...luv seeing old threads brought to life...cheap PH meters are not worth the meager investment...IMHO...especially the triple function meters(light, moisture, PH)...personally I prefer test strips or powdered reagents...no calibration required...butt...that's just me...cheerz...h00k...
Been my experience so far as cheap pen I bought is all over the place with the same exact water minutes later or day later. The strips work well for me to get it close enough for what I"m doing, the drops I was having trouble telling color after Nutes put in. Kind of opposite direction
but as the Leadman would say at the Lumber Mill "Measure it with a Micrometer, mark it with Chalk, and cut it with a Chainsaw" 
