PH meters

Looking to buy a Ph meter for the garden. Seen this one on ebay
http://www.ebay.co.uk/itm/3-in1-Pla...denEquipment_HandTools_SM&hash=item4171c15330

Interested if anyone has used one and are they any good

TIA

 

Its a bit similar to the one I have. I've got this one:

http://www.amazon.co.uk/Silverline-...=UTF8&qid=1397312467&sr=8-3&keywords=ph-meter

Works fine, but the thing with these meters is that people often dismiss them as rubbish because they haven't used them correctly.

The soil you are testing has to be very wet. Pour at least a pint of water into the spot you're going to test and give it a minute to soak in. Then in goes the meter, which of course is very clean because dirty probes will give you an inaccurate reading. You then need to leave the meter in place for at least a minute before you take a reading.

Its all down to electro-chemical reactions. Like a battery. You have two different metals (on the probes) and when you stick them in the ground, an electrical current will start to flow. The current is directly proportional to the pH. The current flows because water is conductive, and the water will turn either acid or alkaline depending on what its dissolved (its all about cations in the soil minerals). This is why, if the soil is too dry, the current wont flow (or will be very impeded), and if the water hasn't had time to dissolve the minerals into a suspension, you'll be measuring the pH of tap water, which is pretty close to neutral, even if your soil is very acid or very alkaline.

Its like if you pour vinegar on bicarbonate of soda. At first nothing happens. Its only when the vinegar has had time to dissolve the bicarb that you get the classic volcano effect.

 

OK if you keep moving, if you stay in one place you dont really need one.
Once you know the soil ph of your garden its not likely to vary wildly, so could be better to get a ph testing kit if you are unsure of a new garden.
Not a great fan of meters, although I did buy one years ago, not sure where it is now, in the back of a drawer in the greenhouse I think.

 

I'm not a fan of meters either, although C1's experience is interesting, hadn't thought of that before.

Main issue I have with meters is how to know if they are calibrated? When I have used one in a lab the first thing we did was to calibrate it with solutions of known-pH.

Although the colours can be a bit hard to gauage, against the provided colour-chart, I find the test-tube style kits suit me better for the occasional use I have for them.

I do test some beds in my vegetable patch occasionally - to see if they might need liming as yet. And I figure I'm going to test part of my Hydrangea bed, where I want blue flowers, to see if I am managing to acidify it at all with Sulphur.