↠ Guide to replacement electrodes for your pH meter - for home brew

How to select a replacement pH Tester electrode

Many keen beer brewers like to know the pH of their brews so they can ensure the kind of beer they want to make, is the one they are making!

A good pH meter will go a long way to ensuring the water and wort are what the brewer needs.

A pH meter that is well-used will eventually need its probe or electrode replaced.

If you're here to simply find a recommendation for a good replacement probe electrode, here are your best buys for some common testers:

• Apera-Instruments-AI1203-PH60F-Replacement
• Bluelab pH Replacement Electrode for Combo & pH Meter
• Milwaukee MW102 PH and Temperature Meter
• Hach Pocket Pro + Ph meter
• Hanna Instruments HI 98128
• Oakton WD-35624-38 Oakton Replacement Sensor
• General probe replacement options

Why do pH probes wear out?

There seems to a little bit of misunderstanding on a couple of brewing forums about the use and usefulness of pH meters.

You can often find commentary and reviews that they are 'inaccurate or don’t work at all' "I can't get this thing to work properly, I shouldn't have cheaped out!"

I suspect that the vast majority of ‘incorrect’ readings and measurements are quite possibly due to poor management and maintenance of the electrode and this is mostly directly due to incorrect storage of the probe.

How to clean your pH electrode

It's a very wise practice to regularly clean your pH electrode. This is because a coating will otherwise develop on the glass bulb. This layer is known as the hydrated layer and it will quite likely cause inaccurate measurements and drifting or erratic readings.

It does this by generating a different voltage in a pH buffer than a pH electrode without a hydrated layer.

You can imagine how frustrating that will be for brewers trying to get accurate results!

The standard manner in which to clean the electrodes s by simply placing them in a cleaning solution for 15 minutes.

It's the same concept as contact lens soaker! The cleaning solution dissolves the build-up.

After the cleaning solution has done its business,  the probe must be rinsed with very clean or purified water and then placed in probe storage solution for at least 2-3 hours before using.

Our recommended manufacturer Bluelab, who makes the fantastic Combo Meter has a pretty handy probe cleaning kit.

The Bluelab Probe Care Kit contains everything you need to clean, hydrate and calibrate your unit's pH probes

Each cleaning kit contains:

• Pack contains 2 x 20ml sachets each of pH 7.0, pH 4.0, EC 2.77 and KCl storage solutions
• Probe cleaners 
• Probe cleaning tools 
• Plastic cups 
• User instructions

How to store and protect your probe to maintain its life

Your probe is the consumable and probably the most expensive component of your pH meter.

There are two key things that you can do to help ensure that you get a long and useful life out of the probe.

Number one - keep your electrode in a fresh storage solution.

We mention this elsewhere in this article because it is so important! We wonder how many dudes are buying replacements because they dried their meters out!

If you're an 'every so often' brewer and you don’t use your meter for an extended period of time, bear in mind that you will need to change the storage solution around every 6 weeks or so.

Fresh is best!

A word or seventeen of warning. You should never ever ever consider storing your electrode in water!

Why would you do this crazy thing?

How it all works is that the reference cell has a high salt solution. By placing the probe in purified water, it will cause the salt to diffuse out and the water to go in. You do not want this to happen!

Storage solutions are designed to maintain the reference salt concentration but they also have handy chemicals present to keep bacteria and fungus from growing in the solution.

So, if you do use it for some unfathomable reason and decide to use water, electrolyte solution will leach out of the meter and shorten its lifespan. At a real pinch, when a storage solution is not available, then you may be able to get away with using pH 4 buffer - I'd suggest you only do this for a short term while you are getting some genuine storage solution for the unit.

Remember, these parts are expensive so it's on you to take care of your brewing equipment.

Secondly, for goodness sake - be damn careful with your probe!

These things are bloody fragile. Take good care not to allow it to physically bang into the wall or rim of your testing vials, as this could damage the membrane.

And you know, don't drop the damn thing!

What is a buffer solution?

A buffer solution is one which resists changes in pH when small amounts of acid or alkali are mixed with the buffer.

Acidic buffer solutions are commonly made from a weak acid and one of its salts*  - often a sodium salt.

Why you need to use fresh calibration solution

One should always use fresh calibration solution when calibrating one's pH electrode. All pH measurements are based on the pH calibration solution as a reference point so the solution needs to be pure and not contaminated.

The pH calibration buffer is a water-based solution that will change over time. This is especially true for the pH 10.01 buffer that actually decreases in pH as atmospheric carbon dioxide enters the solution.

Natural product evaporation will change the pH level of the solution too.

Opened bottles of buffer solution should be dispensed with after they have been opened for 6 months. 

Once you have calibrated your beer wort, dispose of the reference calibration solution as it can contaminate the remaining fluid if you add it back!

Fresh is the best!

How do pH probes work?

The principle idea of the pH meter is that it measures the difference in electrical potential between a pH electrode and a reference electrode. The difference in electrical potential relates to the acidity or pH of the tested solution

Why does my new pH probe have a kind of salt like residue on it?

A deliberate salt residue is often placed around the probe as a protective shipping solution so what you may be seeing is normal. Before calibration,  rinse the salt off and let the probe soak for an hour in 4.01 calibration solution, storage solution or bottled water and then follow the calibration procedure instructions of your meter.

Do you know who invented the pH meter?

The concept of pH was first mooted by S. P. L. Sørensen in 1909. Following this discovery, electrodes were developed and used. The first commercial application of a pH meter was by Arnold Orville Beckman who in 1934 was granted the first patent for a meter. 

His company sold 444 units 2 years later and then when on to sell millions of units, making his name and fortune in the process.

Here's what an original Beckman pH meter unit looked like. Can you spy any replaceable probes?

Image credit found on Wikipedia and attributed under a Creative Commons license by the Science History Institute.

How often should I calibrate the meter?

To obtain the most accurate results, you should calibrate before each use or set of uses. However, most units will hold calibration very well. If you get a reading that is above or below what you would have expected, then check the calibration at that point and retest your beer solution!

Leave a Comment bluelab, buffer solution, calibration, calibration probe, calibration solution, electrode

Bluelab pH Combo Meter - Review 2020

Review: Bluelab Combo Meter for your pH measuring needs

If you are looking for an upmarket solution to measure and meet your pH solution needs then the tried and true Bluelab brand has the measuring device you are looking for:

Bluelab has a reputation for making devices that help with crop management, soil testing, nutrient meters, and home-based hydroponics.

It's apparently really popular with marijuana enthusiasts in California and kombucha makers everywhere!

The Bluelab Combo Meter has the triple functionality of being a portable pH tester, conductivity reader and temperature taker all in one. This can be quite a handy combination for home brewing
enthusiasts!

The meter has two probes, a Bluelab pH probe, and a Bluelab Conductivity and Temperature probe. When taking a reading, simply place them into the solution and the selected reading is displayed on the screen. 

Dead easy.

The beauty of the Bluelab system is that all their probes are compatible with their entire range. As with most decent pH testers, you'll need to purchase probe storage solution to maintain and prolong the life of the probe.

Calibration of the pH probe is quite simple as instructions are supplied on the back of the meter and the easy 'push button method' makes this one of the simplest meters to use for your brewing needs.

That said, there are plenty of mistakes people make when using meters, especially when calibrating.

The pH probe is quite replaceable so you can use this meter for many years to come. You should be able to do this as Bluelab offer a 5 year warranty on their product!

This surely gives you an idea as to the quality of the product and the faith the brand has in it. 

By utilizing the temperature function of the unit, you'll be able to take accurate readings during the boil and quite importantly, after you've cooled the wort sufficiently, you'll be able to record the correct temperature at which to pitch the yeast - old hands will know that if  you pitch yeast into a wort that's too hot, you will kill the yeast and no fermentation will begin. 

The Bluelab meter has the following features:

• Measures pH, conductivity / nutrient (EC, CF, ppm 500 and ppm 700) and temperature (°Centigrade & Fahrenheit)
• It's very lightweight and portable
• Large easy to read display screen
• Simple push-button operation for pH calibration
• Successful pH calibration indication
• No calibration is required for conductivity and temperature measurement taking
• The double junction pH probe is easily replaceable 
• Over range and under range indicators
• Low battery level indicator
• Two x AAA alkaline batteries included so you can start taking measurements immediately
• Auto off function to make sure that the battery doesn't wear down.
• Five year warranty for the unit itself, and six months for the probe.

Because of its demonstrated quality, this is a pricey unit but well worth it if you are a regular brewer who needs to monitor the hydrogen potential of their beer!

If you are looking for a mid-price range metering device, Blue Lab's portable pens are in the hundred dollar range. They are quite portable and come with a conductivity probe care kit.

Here's some reviewer comment from happy buyers on Amazon:

"I am going on 6 months and it hasn't even needed to be re-calibrated."

"Very accurate. Nice meter, the ph probe is extremely fragile, do not tap this probe on anything or it will break" (This is a pretty common occurrence with most glass probes so is not necessarily a design flaw in the product and replacement is an easy process - Ed)

"Be sure to do the recommended meter maintenance and proper storage of probes."

"Recommended if precision means everything to you! Calibrate twice a month minimum if used daily, and buy some storage solution for the probe! It doesn't come with any extra storage solution, but it is a MUST to get some as well as extra 4.01 and 7.01 buffer solutions and you're set for a while!"

And finally this absolute gem of a product endorsement & review from a user:

"Easy to use. Worked right out of the box. Easy to calibrate and maintain. I'd wanted one for years but didn't want to spend the $$. Well, I'll tell you, it was worth it. I never knew how far off I was with just using measurements and test strips. The next batch that I produced using accurate measurements with the combo meter was astounding. Try it and see the difference."

Try it indeed.

Here's the official video from Bluelab which shows you how to prepare the meter for its initial use and how to correctly calibrate the device with the proper buffer solutions.

When should I clean the Blue Lab ph Meter?

For accurate pH readings the pH probe should be properly cleaned and then re-calibrated when:

• when the on screen reading is quite different from what you were expecting. 
• when the batteries have been run flat, removed or changed. This is because the device forgets its readings.
• when the pH probe is replaced with a new one or is disconnected from the Combo Meter.
• the pH calibration indicators have disappeared from the unit. 

When calibrating the pH after the machine's first use, the pH probe needs to be cleaned after each subsequent use.

How to correctly calibrate the meter

To obtain a correct pH calibration reading, the unit's accuracy is very dependent on the accuracy and age of the calibration solutions used, and the condition and cleanliness of the pH probe tip. You will get a calibration error if the unit is not properly maintained as per the instruction manual.

For best results, the user must ensure the pH probe has been cleaned and that it is rinsed with clean water between calibration solutions to reduce contamination of the pH solutions.

One should only use fresh and uncontaminated solutions. This means if your buffer solution has been sitting open on a shelf for a couple of years, you probably should obtain a new batch.

It's also best practice to calibrate the pH at the same temperature as the solution to be measured. 

If you're not sold, you could consider these ph pens or check out our guide to five other top rated pH Testers.

Leave a Comment bluelab, buffer solution, calibration, conductivity, ph pen, ph tester, temperature, water testing

↦ Using calibration buffer solutions to calibrate a pH meter

How to calibrate a pH meter using a buffer solution

While beer making can be a bit of a science, taking the pH level of your beer or water is like some kind of advanced astrophysics lesson because it seems so complicated, what with all the calculations and formula.

Some guy called Nernst apparently had a lot to do with it.

While a pH reading can be complicated because a serious brewer needs to properly calibrate their pH meter - the actual 'maths' involved is straightforward - especially when a proper reading is taken which then means the brewer can make an informed judgment call about how their beer is going.

And to calibrate your meter, you need calibration or buffer solution.

What is a calibration buffer solution?

A calibration or buffer solution is a chemical solution that is used to calibrate a pH meter.

A buffer solution is one that resists changes in pH when small amounts of acid or alkali are mixed with the buffer. Acidic buffer solutions are commonly made from a weak acid and one of its salts - often a sodium salt.

The buffer is used to develop a calibration curve. This a scientific method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration

In the case of calibrating a pH meter, at least three 'standards' are needed.

Without the standardized pH buffer to calibrate the meter, the results will not be accurate and thus give you the wrong impression.

pH meters tend to 'drift away' from their calibrated settings, it's just their nature due to the way science works!

It is thus very important to calibrate your pH meter often so that the accuracy of your results is maintained.

Devices other than pH meters need calibration with a solution too, such as refractometers and conductivity meters.

What are standard buffer solutions?

The definition is that standard pH calibration solutions should have an accuracy of +/- 0.01 pH at 25°C (77°F) and come usually in seven different pH values from 1.68 to 10.01.

The most popular and commonly used buffers are (4.01, 7.01, and 10.01). Good brands are dyed different colors so they can be easily identified by the brewer and thus used in the correct order.

Standard buffer solutions can be used to calibrate almost any common pH meter so you don't need to fall into the trap of say, for example, using a Hanna brand buffer for a Hanna meter.

The Milwaukee MW102 is pretty popular too! And let's not get started on how big a seller the Apera is!

This does mean that you can look at price and value per mls when deciding what brand to use.

There are two other kinds of calibration standards - Technical and Millesimal

Technical solutions come with a certificate of analysis (COA) which affirms that the solution will absolutely perform to the standard as described.

Millesimal calibration solutions are used in labs where accuracy down to three decimal places is required, think along the lines of municipal drinking water plants, and medical research facilities where readings can be absolutely crucial to good human health outcomes!

Homebrewers generally just stick with standard calibration solutions which they often order online from Amazon.

Why you need to use fresh calibration solution for pH testing

Brewers and testers should always use fresh calibration solution when calibrating one's pH tester electrode. 

All pH measurements are based on the pH calibration solution as a reference point so the solution needs to be pure and not contaminated. 

Think of this like contact lens solution, when it gets old, you don't use it to clean your lenses, you bin it and go with a fresh batch.

It's generally recommended then that opened bottles of buffer solution should be dispensed with after they have been opened for 6 months. 

The higher the buffer's pH ( from  > 7 ), the quicker it will degrade.

If you are calibrating fairly infrequently, you may wish to consider using single-use solution sachets rather than bottled.

How do I use a calibration solution?

Your meter's pH electrode should ideally be cleaned in purified water before placing it in your pH calibration buffer. This reduces the chance of contaminating the solution

A good practice is to be to use two beakers/containers for each calibration buffer that you will use.

Your method would be to clean the pH electrode with purified water then rinse the probe in one of the beakers with the buffer then place the probe in the second beaker with the buffer.

Repeat this practice for multiple calibration points.

For best results, the user must ensure the pH probe has been cleaned and that it is rinsed with clean water between calibration solutions to reduce contamination of the pH solutions.

Here's a handy video guide on how to use your meter with the buffer:

If your solutions are clear, make sure you mark them out before you begin calibrating! You could leave the bottle or sachet close to the beaker as a reference. 

To obtain a correct pH calibration reading, the unit's accuracy is very dependent on the accuracy and age of the calibration solutions used, and the condition and cleanliness of the pH probe tip. You will get a calibration error if the unit is not properly maintained as per the instruction manual.

Never reuse calibration solution

Once you have calibrated your device and then tested beer wort, you should dispose of the reference calibration solution.

Given it has been exposed to the environment and has had equipment placed in it, there's a fair risk of contamination - so adding that to your original sample can risk ruining all your fluid!

The same applies to reusing the test sample at a later date. 

Just don't chance it.

Check out these common ph testing mistakes for other ways to avoid screwing up. 

Making homemade calibration solutions

While some brewers can try to make their own DIY solutions to save money, the results prove to be homemade buffers that are not accurate or stable. This is a wasted effort as the buffer can be guaranteed to interfere with the accuracy of the test results.

Thus, we don't recommend you try to make your own! Check out the options available on Amazon.

Leave a Comment buffer solution, calibration, calibration solution, electrode, ph meter