# Noob with a pH pen



## lilirose (28 Oct 2020)

I bought a pH pen a year ago for about 15 quid, bought it to do quick convenient checks, however I didn't find it convenient at all in the end because I can't be sure of its accuracy, so I set it aside.

The instructions say "The pH meter needs to be recalibrated in the following situations: it is not used for a long time, the use of electrodes is particularly frequent, the measurement accuracy is relatively high."

Now I realise this was probably written by someone who does not speak English as a first language, but it sounds like I need to recalibrate it if I don't use it often, but I also need to recalibrate it if I use it frequently, and I also need to recalibrate it if I want it to be accurate. It sounds like I will need to be constantly recalibrating, and I can't wrap my head around how to do that easily.

I used the thing about twice and then stuck it into one of my "baskets full of random aquarium stuff" because of the above. However I am now running a couple of high-tech tanks, and this pen would be really useful if I knew how to tell that it needs recalibrating, how often that's likely to be, and how to do so easily- I have the little sachets of 4.01 and 6.86, should I have a couple of bottles mixed up permanently like I do with the recalibration fluid for my TDS meter?

Anyone able to enlighten me? Am I overthinking as I do with everything?


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## Nick potts (28 Oct 2020)

You can get larger premixed bottles of ph calibration fluid on amazon etc, or you could make your own.

But in all honesty, the cheap PH meters tend to be more hassle than they are worth and it might be better to just get a decent liquid kit. The cheap ones tend to be hard to calibrate and don't tend to hold calibration for long, you just end up not trusting the result anyway.

If you want a decent meter and don't mind paying a bit more I can recommend Hanna instruments and Milwaukee


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## lilirose (28 Oct 2020)

Nick potts said:


> You can get larger premixed bottles of ph calibration fluid on amazon etc, or you could make your own.
> 
> But in all honesty, the cheap PH meters tend to be more hassle than they are worth and it might be better to just get a decent liquid kit. The cheap ones tend to be hard to calibrate and don't tend to hold calibration for long, you just end up not trusting the result anyway.
> 
> If you want a decent meter and don't mind paying a bit more I can recommend Hanna instruments and Milwaukee




I have the API liquid kit that I use as standard, but I've read much on here about doing a pH profile and testing every 30 minutes, which would require dedication with a liquid kit- though to be fair, the liquid kit is instant. 

I think I'll be asking for one of those Hanna ones for Christmas, if they come back in stock...


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## Zeus. (28 Oct 2020)

pH pens and accuracy...... IMO why do they need to be accurate for what we are using them for? does it matter if its out by say+/- 0.5pH what difference does it make ? what different would you do if it said 7.1 or 6.6pH?

If all you are using it for is to check that the pH is stable during the current photoperiod. If the next day its at a different pH going of the pH pen what does it matter as long as it stays relative stable from lights on for the first 5 hours of the photoperiod. As long as the DC changes the colour we are after and the pH reading is stable - job done IMO


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## lilirose (28 Oct 2020)

Zeus. said:


> pH pens and accuracy...... IMO why do they need to be accurate for what we are using them for? does it matter if its out by say+/- 0.5pH what difference does it make ? what different would you do if it said 7.1 or 6.6pH?
> 
> If all you are using it for is to check that the pH is stable during the current photoperiod. If the next day its at a different pH going of the pH pen what does it matter as long as it stays relative stable from lights on for the first 5 hours of the photoperiod. As long as the DC changes the colour we are after and the pH reading is stable - job done IMO




This is why I mentioned "noob".  I have drop checkers. I'm honestly not at all sure why people are doing pH profiles but by God I want to be ready to do one if necessary!


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## Zeus. (28 Oct 2020)

pH profiles are very useful to check the [CO2] is stable, but no where does it say the pH measurement needs to be accurate pH reading.


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## lilirose (28 Oct 2020)

Oh, right, got it! So I can trust this cheap pH pen for that purpose? I've a tank that has no fish in it yet, actually was thinking a pH profile would be useful before I add any stock.


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## Nick potts (28 Oct 2020)

Zeus. said:


> pH pens and accuracy...... IMO why do they need to be accurate for what we are using them for? does it matter if its out by say+/- 0.5pH what difference does it make ? what different would you do if it said 7.1 or 6.6pH?
> 
> If all you are using it for is to check that the pH is stable during the current photoperiod. If the next day its at a different pH going of the pH pen what does it matter as long as it stays relative stable from lights on for the first 5 hours of the photoperiod. As long as the DC changes the colour we are after and the pH reading is stable - job done IMO


Some pens lose any meaningful accuracy very quickly, some just are no good to start with, I have seen them read up to 2 points out on the same tank just checked 5 mins apart.

Also, some people like to have a degree of accuracy over parameters (and the tools are there if your willing to pay), for instance my tap water is basically 0kh and 0gh but has a very ph ph, when i add buffer this affects the PH which i like to keep an eye on.


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## dw1305 (29 Oct 2020)

Hi all,


Nick potts said:


> Some pens lose any meaningful accuracy very quickly, some just are no good to start with,


I'm not a CO2 user, so I don't have any practical experience of measuring the pH profile as the amount of CO2 (H2CO3) increases. Because you are around the pH neutral point (pH 7) there are more possibilities for inaccuracy, mainly due to the log^10 nature of the pH scale.

Personally I would be reluctant to use <"a cheap pH pen">, and even with more expensive meters you still need to <"calibrate them before every use">, store them in the <"correct storage solution"> etc.

cheers Darrel


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## lilirose (29 Oct 2020)

I certainly learned within about five minutes of buying the thing that it would not make my liquid test obsolete, exactly because of the log^10 mentioned by @dw1305 . When I bought it, I had some rocks in the tank I was not sure about and thought it would be a quick and easy solution for determining if my pH was affected over time- more so because the API liquid pH test kit has a "break" between the low-range and high-range tests that made it difficult to closely monitor. Of course I should be suspicious of anything in this hobby that seems quick and easy.

As it turns out, the liquid tests were good enough, and the rocks are fine - have been in my tank for a year and a half now with no ill effects to soft-water inhabitants. I rarely check pH on my established tanks these days, maybe a couple of times a year so those fancy spreadsheets I set up when cycling don't go to waste. 😆 But now that I'm experimenting with high-tech, maybe I have a touch of gadget fever?


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## dw1305 (29 Oct 2020)

Hi all, 


lilirose said:


> maybe I have a touch of gadget fever?


You need to spend a reasonable amount to get a good pH meter. I've considered buying a solid state ISFET meter, but I can't really justify the cost, particularly because I have access to fairly swanky desk-top meters that I never use anyway. 

Have a look at <"pH monitor suggestions....."> for a more complete discussion. 

cheers Darrel


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## Nick potts (29 Oct 2020)

lilirose said:


> I certainly learned within about five minutes of buying the thing that it would not make my liquid test obsolete, exactly because of the log^10 mentioned by @dw1305 . When I bought it, I had some rocks in the tank I was not sure about and thought it would be a quick and easy solution for determining if my pH was affected over time- more so because the API liquid pH test kit has a "break" between the low-range and high-range tests that made it difficult to closely monitor. Of course I should be suspicious of anything in this hobby that seems quick and easy.
> 
> As it turns out, the liquid tests were good enough, and the rocks are fine - have been in my tank for a year and a half now with no ill effects to soft-water inhabitants. I rarely check pH on my established tanks these days, maybe a couple of times a year so those fancy spreadsheets I set up when cycling don't go to waste. 😆 But now that I'm experimenting with high-tech, maybe I have a touch of gadget fever?


I think everyone is like that at the beginning, I remember have test results written down everywhere, sticky notes on the inside of the tank cabinet doors with reminders etc, after a while, you tend to just watch the tank and notice if something is off. There are of course always times when you might want/need to check something. And there is wrong with a case of shinyitis 😄


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