PH Meter

[solly]

Following on from what koomber was saying about acidity testing with a PH meter Here

I already have the Riches Acid test kit but I dont believe that its 100% accurate as its hard to tell when a colour change occurs.

With this in mind I am looking a buying a PH meter and just wondered if anyone has any experience in using these for Wine making and what range etc I should be looking for - also seen a few on Ebay as well as Farnell and RS

Ebay

Farnell

[NorthernWiner]

Solly,

I have a nice benchtop meter I've been using for a couple of years. I recommend getting one with an accuracy to pH ±0.03 and a resolution to two decimal places.

While accuracy of ±0.1 seems like it would be plenty, in winemaking, that's not quite good enough. For example, if you take a reading and it says the pH is 3.6, it could be anywhere from 3.5 to 3.7. That might be good enough for ballparking, but 3.5 is borderline too low and 3.7 borderline too high.

Also note that neither of the ones you're looking at have a replaceable probe. What that means is that once the probe wears out (they last an average of about 2 years) you have to bin the meter and buy a new one.

Something like this would be a better choice, in my opinion...

http://uk.farnell.com/testo/206-ph1/ph-meter/dp/8369089

[NorthernWiner]

Actually, looking again at the Hannah, it does appear to have a replaceable probe.

But I would still look for a unit with better accuracy.

[solly]

Thanks for the advice Steve, after reading your thoughts on the spare probe, I checked on the RS site and they sell a Hanna version for £62.00 plus you can also buy a spare probe for £40.00 (not cheap this business)

The accuracy seems better as well at 0.1ph - Just one other thing I did think about was a plug in probe into a Multimeter as I already own a couple of these (these read voltages, resistance, current etc)


RS PH Meter

Spare Electrode


EDIT: might just have found a better one on Ebay - you can buy a spare electrode and the accuracy is 0.03PH
Ebay Item

[koomber]

You really need to decide how far you plan to go with this. If you are going for mega accuracy your going to need calibration fluids.

Calibration fluids are usually sold as tablets which you dissolve in a fixed volume of deionised water. Once dissolved the solution will have a fixed pH of (usually) 4, 7 or 10 depending on the tablet. You need 4 and either 7 or 10 to calibrate effectively. These solutions are buffered. That basically means that they have a limited ability to resist changes in pH due to contamination.

Without calibrating a pH probe your going to find your accuracy will vary way more than 0.01, so buying one this accurate is pointless without the calibration solutions. How often you calibrate depends, but in my work lab we calibrate every time we run the test, then again we have a fair amount of the fluids.

The more expensive desktop ones are usually a bigger pain for this since they tend to be able to factor in temperature too. Some have a thermocouple included others (shudder) need a thermomoter.

The second point is what you are going to meassure. if it is pH and you have the calibration fluids then go buck wild and get yourself an expensive probe*. If it is a titration using a RITCHIES or (Koomber ) test kit then I wouldn't bother. Why? Well....

I'll get a post on why since it is a bit involved, but baically, with what you can do with a couple of syringes the errors from operator error are going to translate to HUGELY more than 0.01 pH. And that assumes that everything else is perfect. RITCHIES test kits are ballpark at best so if you are testing with this you rally don't need a mega accurate tester.

This is my humble opinion and is biased heavily by my views as a chemist, as such it may have very little relevance in the world of wine making, but from where I'm sitting, I wouldn't get a mega accurate tester.

*I'm working on the maths atm, but I don't see there being a need here either.

[NorthernWiner]

This is just my opinion as well, but I really think that if you're going to spend £60 for a meter that's accurate to ±0.1, why not spend another £30 and get one that's accurate to ±0.02?

In winemaking, most musts & wines fall between pH 3 and 4. While the pH scale is logarithmic, that's still a somewhat narrow range. That's where the accuracy comes in useful.

But I agree that if the only thing you are doing is simple TA titrations, where the endpoint is "roughly" pH 8.2, then a high degree of accuracy is probably not a necessity.

I was lucky enough to find a used ORP benchtop meter on eBay a few years ago that's accurate, quick, and stable. I calibrate it every time I power up, but find that most times it's still dead on - even after a few months of not using it. One of my favorite pieces of kit.

[koomber]

I was lucky enough to find a used ORP benchtop meter on eBay a few years ago that's accurate, quick, and stable. I calibrate it every time I power up, but find that most times it's still dead on - even after a few months of not using it. One of my favorite pieces of kit.

Jammy So and so!

But you do have a good point. You get what you pay for. A Good piece of kit will be more reliable, last longer and be more comfertable to use than a cheap piece of kit. I'm just presenting the view point of a Exceptionally tight fisted Scotman. Can't be spending those pennies!

[kampervan]

yeh but is wasting £26 on ebay one a waste or will it give same sort of results as richie's kit

[solly]

yeh but is wasting £26 on ebay one a waste or will it give same sort of results as richie's kit

Might just be me (maybe I just need extra training or watch some extra Utube videos) but personally I think the Riches test kit is a waste as I used it once and because it seemed so hard to use, it's now sat in the cupboard and more then likey wont get used again - hence the reason for looking for something that is far eaiser to use then the test kit.

I just really want a piece of kit that is quick and easy to use without having to mess around using syringes & colour charts and I dont mind spending a little bit of money to help me achieve a balanced wine.

To be honest I did'nt know what to look for in a PH meter (but know a lot more now), hence the reason for the post and a PH meter wont appeal to many people because of the cost - but if you want to understand and improve your wine then you will need some tools to help you get there

[Cellar_Rat]

I bought one of the bright yellow pen type £10 ebay jobby's and it has proved to be accurate enough for me for a few years now.

Also recenty bought a Lutron PH Meter that seems ok - separate probe for titration.

Again auto cal seems OK- and quick to respond.

[solly]

Got me PH Meter today from Farnell

http://uk.farnell.com/extech-instrum...1?Ntt=127-1521

Just wondered what reading I should be looking for? and what to add it's below the reading and what to add if it's above the reading?

[NorthernWiner]

Solly, that's a nice looking meter. The specs on it look good as well.

Your question is very general, so I'll give you an equally generalized answer.

In general, wine and must should have a pH of between 3 and 4. The ideal pH is dependent on the type of wine. White wine should have a pH between 3.2-3.4. Red wine's pH is usually higher, with a range between 3.5-3.7. Fruit wines tend to be closer to white wine parameters. Low pH indicates higher acidity, and conversely, high pH means lower acidity. If wine has too high of a pH (low acidity), it is more prone to spoilage. Too low of a pH, on the other hand, can mean tart, undrinkable wine. The key is to find proper balance.

If your wine has a high pH, it can be corrected by adding acid. In winemaking, tartaric acid is preferable over citric or malic because it's a stronger acid and takes a smaller amount to cause a shift in the pH. It's also more "wine like" than other acids.

If your wine has a low pH, then you can take measures to lower the acidity. This isn't quite as straightforward as adding it. There are a number of methods that can be used, including blending, cold stabilization, or chemicals (calcium carbonate, potassium carb/bicarb, etc).

Again, these are generalizations, so when in doubt, ask questions.

With regard to your meter, I realize you didn't ask the question, but make sure that you store the meter with the probe submerged in a storage solution. The number one cause of damaged/worn out probes is allowing them to be stored dry. If you didn't purchase any storage solution, you can use pH 4 calibrating solution. Just don't use distilled water. Though you'll occasionally see it suggested, it will quickly deplete the electrode.

Here is a link to a document containing information on the proper care of a pH meter.

http://www.morewinemaking.com/public/pdf/wphmeter.pdf

You can also use your meter to test the TA (titratable acidity) of wine. More details in this PDF (scroll down to the section entitled "Determining the Endpoint by pH").

http://morewinemaking.com/public/pdf/acidtest.pdf

Hope this at least gets you started.

[NorthernWiner]

By the way, if you guessed that I like these MoreWinemaking manuals, you would be correct.

More here: http://morewinemaking.com/content/manuals

Good reading, this.