Is it just me or are PH probes a bit of a con?

I bought a cheapish one, for £50, and it's gone haywire after only a few months, and not even really used. For example I know my tap water is about PH 7.4 and on first testing, and calibrating that was all good.

But now when I come to use it properly its all over the place, It can read anywhere from PH4 to PH9, despite re-calibrating it in PH7 calibration liquid, and now it's displaying what looks like an error code, so I guess it's busted, maybe I let the sensor dry out?

So I've just bought a more expensive 'blue labs' reader for about £75 and a pack of paper testers as a back-up. I already have a bluel ab EC reader and it seems really good and accurate.

I understand with the PH readers you should keep the sensor wet with the 'stabalising fluid' but even then, they say they might not last more than a year or so, before they expire.

They seem very expensive for what they are, do you all use these? or do you use litmus paper tests or swimming pool ph tests? The swimming pool test kits only go down to about PH6.8 so probably useless for hydro.

Thanks for any advice.

Sounds like you haven't been using storage solution.

I think you might be right. I didnt realise how sensitive/fragile they are... do you have to keep the sensor permently submerged a cup of storage solution?

Thats gonna be a pain in the ass! lol! does it evaporate?

futurebanjo said:

I think you might be right. I didnt realise how sensitive/fragile they are... do you have to keep the sensor permently submerged a cup of storage solution?

Thats gonna be a pain in the ass! lol! does it evaporate?

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No, you just put a few drops in your pen cap each time you are done using it.

Ok cool, thanks, I've bought some storage solution along with the new PH stick. (i'm pretty sure my old one is ruined, that was an expensive lesson!) That makes things a bit simpler, Thank you.

Apera Ph60 meter cost me £70 iirc last July, when I bought it I also bought a spare tip/probe £30.

I calibrated it yesterday when I put it into ph 7.0 it read 7.1 that's with the original probe/tip, it's important to care for it with the right storage and ph solutions.

Ahh, good point, I should probably try to buy one with a replacable probe, this is the new one I just bought, but I don't think you can replace the probe on it: https://bluelab.com/united_kingdom/bluelab-ph-pen

I store my pH pen in a coffee cup that's got a few ounces of nutrient solution in it.

I wouldnt waste my time with a pen when this (or similar) costs $10 and last a couple of grows.

For anyone taking regular readings ph pen/meter are the way to fine tune ph, imo using a ph test kit to fine tune is a real pain and it's time consumimg doing multiple tests.

I wouldn't be without a test kit but it's only a back.

I was having my ph meter fluctuate all crazy until I realized one of my submersible pumps used for stirring was the culprit. It bounced very quickly back and forth until I unplugged the pump. It would be worth a shot seeing what happens after u shut off any powered things going in the reservoir. Also you want to add some nutrients into the reservoir as these pens don't like reading on clean water

My Apera meter was $39, and was just .2 off after a year without calibration-I've religiously kept the tip in KCL storage solution. As far as the test kits go, I've used them all from my previous experience with aquariums, and if you have trouble reading the yellow/greens of the Hydrofarm kit, try a Sera Freshwater PH kit. It's a bit more expensive, but the colors are so vibrant and easy to read. I keep a kit as a backup for if my pen gets off, of if my reference solution gets old and less accurate. I only check my PH once per week or so (probably don't even need to do that), I just make accurate measurements for my nutrient solution/citric acid and it comes out the same every time.

I rinse the business end with clean distilled water after each use and cap the end wet.
keeping the bulb from drying out is critical to it lasting and staying accurate.

If you use the pH meter daily, then you don't really need to store it in a solution. But if you stored it long term dry, then the ions in the glass probe have leeched out and it's finished. The solution prevents them from leeching out.

My opinion. . ..

If you're not changing what nutrients or water you use, and you can gauge its pH level upon mixing, you can just repeat your mix & loosely count on it just always being the same pH. No need to pH every time.

ismann said:

If you use the pH meter daily, then you don't really need to store it in a solution. But if you stored it long term dry, then the ions in the glass probe have leeched out and it's finished. The solution prevents them from leeching out.

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What is 'KCl Storage Solution'?
KCl, or Potassium Chloride, is a storage and hydration solution for pH pens and probes
Our Bluelab pH Probe KCl Storage Solution is a storage solution designed specifically for use with Bluelab pH Pens or pH Probes.

Storage solution is used to ensure a pH probe is kept in ideal conditions during storage, while the probe is not in use.

Typically, most storage solutions for pH probes contain a mixture of potassium chloride (KCl) and water. Some brands may contain small amounts of other ingredients. For this reason, we try to suggest using Bluelab pH Probe KCl Storage Solutions with all pH probes to avoid contamination from these other ingredients.

Our Bluelab KCl solution only contains pure KCl, which is also at the same mix strength as the gel that is inside our pH probes.

• For this reason, when you hydrate or store your pH probe in our KCl solution, this helps to re-vitalise the KCl reference solution that is inside your pH probe. This is because some of the gel that inside your pH probe can flush out during use - if this happens in storage however, it means that fresh new KCl solution (from your storage cap of your pH probe) will then replace the solution that has flushed out of the probe. This means that the probe is almost 're-vitalised' while it is stored in the KCl solution.

With this in mind, if you are storing your pH probe in tap water or any other solution, then, during storage instead of contaminated KCl flushing out and fresh KCl going in, instead what you'll find is your storage solution (be it tap water or maybe pH4 solution) will be going into your probe instead. This will then worsen the contamination of the internal reference solution!

• Ideally, if fresh KCl is used in storage, then this ensures fresh KCl solution is also what will make it's way into your pH probe, assisting the probe rather than affecting it poorly.

De-ionized, distilled, Pure or RO (reverse osmosis) water should never be used to store or hydrate a pH probe or pen. Pure water will affect the chemistry of your reference solution inside of your pH probe, and this will cause the probe or pen to fail prematurely.

We recommend daily use of the pH probe storage solution - fresh application is recommended once per week (a few drops in your probe storage cap at the end of every week should be sufficient).

Good info, thanks, I bought a bottle of this, says it's 3 mol per liter, dunno if thats the same stuff that comes with the PH pen that arrived today, only a tiny sachet.

So my new PH pen is now sitting in that as it says to let it soak for 24hrs before calibration/first use.

Just looked it up and I think it's the right stuff, Kaliumchlorid being German for Potassium chloride

futurebanjo said:

Good info, thanks, I bought a bottle of this, says it's 3 mol per liter, dunno if thats the same stuff that comes with the PH pen that arrived today, only a tiny sachet.

So my new PH pen is now sitting in that as it says to let it soak for 24hrs before calibration/first use.View attachment 5213373

Click to expand...

You can also make your own storage solution for cheap, if you search on the net for the recipe.

It's just you.

ahh man this is a pain in the ass.. got my new fancy pants 'blue lab' ph pen, followed all the instructions, soaked it in KCL'24hrs, calibrated it.

first testing was good, but it found my tap water a bit acid... I already know it's slighty alkali, it's consistently a soft water about PH 7.4.

Tested my nute solution and ir reads like PH3!!??

I also bought a bunch of litmus papers and after about ten tests, lol! all suggest my nutes are at about ph5 or 6. SO i'm not gonna do anything else yet.

It's hard to say how good the paper tests are, but slightly on the orange side of green. Now I know they work as I did a pre mix of 5L tap water as an experiment and put about 5-10ml ph down in it, (phosporic acid? 85%) and the test stip went bright red straight way. Like blood red.

I know PH down is strong, but the maths doesn't add up.