I bought a pH meter which is aimed at gardeners ...
In water it read 7 .. (so OK there) ... I tried in in a bottle of white vinegar with is rated at 5% acidity it reads pH 6
Is there a simple home way of testing calibration ?
google diy buffer solutions.
You are very lucky to get that result it was pure chance. Rainwater usually has enough CO2 dissolved to be slightly acidic pH 5 and tapwater is buffered towards alkaline to avoid dissolving the pipes.
(so OK there) ... I tried in in a bottle of white
Vinegar is a fairly dilute solution of a weak acid but it should be about pH 3 or so. You can buy indicator solution or strips of paper for next to nothing that cover the 0-14 range (or selected ranges). eg
Of the things you can likely find on the kitchen/garage shelf. Sodium bicarbonate, carbonate, ammonia and sodium hydroxide (careful) as bases in rough order and acetic acid, citric acid (lemon juice), sulphuric, hydrochloric acid as a strong acids.
Take care with any strong alkali or acid they can be unforgiving.
On 09/09/2012 21:47, Martin Brown wrote:> On 09/09/2012 21:32, Rick Hughes wrote: >> I bought a pH meter which is aimed at gardeners ...
But how would I know what pH reading I should get from them ? i.e is lemon juice pH 1,2,3,4 ?
Fuck me. Orange juice is 3 lemon juice is 2 according to a simple check in Wikipedia. And you mean e.g. not i.e.
Use the cheap paper test strips from eBay instead.
Are you incapable of using Google or something?
In message , Rick Hughes writes
You can get buffer solutions of (IIRC) pH 4.7 and 11 which are the standards used for calibration
I think it's RTFM time. I had one of those some years ago. They are not very good. As I recall the instructions state that they will not work with solutions they will only work when rammed into the soil. They are not proper pH meters which have a porous glass electrode, they work on the voltage generated by the bimetallic tip when in contact with soil and apparently that will not work properly in a liquid.
At the time I had access to a lab with a proper pH meter and the Gardman types produced very odd results when used with pH reference buffer solutions.
Short summary, the Gardman and similar "pH meters" are about as much use as if they had been made from chocolate.
The instructions on mine didn't say anything about 'no liquids" about all it says ... .. "clear away top soil, add water, mix with soil, insert probe, wait 1 minute take reading."
You may be right that it will not be much good.
I wonder if I can get a pH probe to use with a MultiMeter ?
Thnx .... found some on ebay
Exactly what I was after .... Thank you
Sorry that I have upset you so much .... please feel free to ignore any future emails from me.
You haven't *upset* me dear boy, just astonished me that you were unable to discover that for yourself on WinkyPedia or elsewhere. Took me all of
4.27 secs. Hmmm, must be modern education systems.
It took you that long because you knew what to search for. If you know nothing about something, you sometimes don't know where to start.
The question related to ph. So I typed ph into the Wikipedia search box. Simples.
When asking about "pH" that seems like a reasonable search term.
Wiki comes about 4th or 5th after "buy pH sponsored adverts" on Bling.
I particularly liked the first ad hit YMMV
Ads
Ph Urine at Amazon.co.uk
Reminds me of a problem we once had importing some elephant urine for pregnancy tests (got impounded at customs). Delay was so great that the elephants were obviously pregnant so no-one bothered to follow up. Eight months later we were notified that if we did not go and pay up to collect our goods it would be auctioned off the the highest bidder!
He would have been much better off with paper test strips off eBay. (or a bottle of pH indicator solution) The "soil" pH meter is junk and cannot be relied upon.
When I was at Uni the senior lecturer was researching neural cell lipid changes in humans on poor diets. We got a call from the airport saying he had to go to cargo and talk to the Revenue. They had a case of steel cans consigned to him and were insisting that he open them for inspection. He suggested that they really didn't want to do that because... then some officious prat told him that no one tells the revenue what to do. They got a can opener and opened a can ... of human brains. Apparently the revenue man projectile vomited.
I hope you wrote back, "Are you taking the piss?"
And uk.d-i-y wants to know --- what kind of can opener?
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