# PH pen choosing help and questions



## Hufsa (23 Mar 2022)

I was about to purchase a PH pen from Hanna, I thought I had the choice nailed down but suddenly now I am a bit confused.

The original option has:
pH Accuracy    ±0.1 pH
pH Resolution    0.01 pH

While the slightly cheaper option has:
pH Accuracy    ±0.1 pH
pH Resolution    0.1 pH

For the pH resolution of 0.01 pH to be useful, doesnt accuracy also have to be 0.01? 
If the accuracy is the same on both meters, what is the point of the higher resolution readout?



The customer service rep is also trying to sell me a more expensive meter with a replaceable probe. Is a replaceable probe even needed for our aquarium use if the non replaceable is stored correctly?
The more expensive one has 
pH Resolution    0.1 pH
pH Accuracy (@25°C)    ±0.1 pH



I need buffer solution right, and it seems the bottles are good for 3-4 years after opening. 1 liter and 500ml cost almost exactly the same, so I was thinking to get 1 liter, might as well?
Do I also need storage solution or can I use one of the buffers? 

Is there anything else I need other than the pen and the buffers, or am I good to go?
I would ask the rep but after they tried to upsell me a more expensive pen with the premise that it comes with buffer so "its better if you're only going to use it a few times", I dont trust them fully and would rather get advice from UKAPS


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## Zeus. (23 Mar 2022)

Hufsa said:


> more expensive meter with a replaceable probe.


Handy as then you can just replace the probe and good as new.


Hufsa said:


> Is a replaceable probe even needed for our aquarium use if the non replaceable is stored correctly?


'If' stored correctly should last many years


Hufsa said:


> I need buffer solution right


you need the storage solution and buffers for calibration
I use the cheapo packages




They are not the correct pH as the Hanna ones are, but I feel they are close enough and all I am interested in is the pH change not the actual pH
I have a Hanna pH pen and I do find it a bit of a PITA to calibrate and new probes extensive. I do find my pH controller more handy with a BNC probe which is cheap to replace about £20 and dead easy to calibrate.
I feel I have no need to know the actual pH for my scapes ATM, the pH change is just a proxy to stable [CO2]


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## Hufsa (23 Mar 2022)

Zeus. said:


> you need the storage solution


Is this solution just put into the pen or do I need some sort of special container to put the things in? If there is a DIY option I am very interested as the budget is tight



Zeus. said:


> I do find my pH controller more handy with a BNC probe which is cheap to replace about £20 and dead easy to calibrate.


Which controller would this be?



Zeus. said:


> I feel I have no need to know the actual pH for my scapes ATM, the pH change is just a proxy to stable [CO2]


Yeah I agree, I dont care what my ph is I just want to buy a good enough meter to tune in a stable CO2 level

Thanks for the help, do you have any thoughts about the accuracy thing?


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## Hanuman (23 Mar 2022)

@Zeus. < Poor man PH probe when you lose in crypto >

A PH probe/monitor is my next purchase. < Check this out >

@Hufsa I would be you, I would forget the PH pen. A PITA and they drift, no matter how expensive and fancy they are. Probes also drift but are considered more stable because they are continuously in a solution and they are double junction. I think PH pens are not double junction. This said probes also need calibration once in while too but as @Zeus. said what is important is the PH difference, not really the absolute number.


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## Hufsa (23 Mar 2022)

@Hanuman ive got hella BBA and GTA atm and have been religiously taught that the prime suspect is poor CO2.
So I just want some way of accurately doing a ph profile. Basically I just want to get rid of the algae.
Are you saying to go for a continous meter / probe instead?


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## Hanuman (23 Mar 2022)

Hufsa said:


> @Hanuman ive got hella BBA and GTA atm and have been religiously taught that the prime suspect is poor CO2.
> So I just want some way of accurately doing a ph profile. Basically I just want to get rid of the algae.
> Are you saying to go for a continous meter / probe instead?


Yes. That's what @zeus also suggests. My experience with PH Pens (and I am already on the 2nd)  is that they are painful. You test your water, you get a result. Test your water again 2 minutes later and the result is different. So you test again and again until you get a moreless average number. A pain. Now each time I make a test I calibrate the pen but still then it gives me some odd results at times. Lot's of waste of time for a so so reliability.


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## john6 (23 Mar 2022)

Rather than buy the ph buffer sachets, why not buy the buffer solutions in bottles, works out alot cheaper.
You can buy 250ml of 4, 7, and 10 for under £4 each, even cheaper if you buy as a bundle.


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## Hufsa (23 Mar 2022)

john6 said:


> You can buy 250ml of 4, 7, and 10 for under £4 each, even cheaper if you buy as a bundle.


Ah can you link me this?
I am located in Norway, so sometimes the options over here are much more expensive, especially shipping from abroad



Hanuman said:


> Yes. That's what @zeus also suggests. My experience with PH Pens (and I am already on the 2nd)  is that they are painful. You test your water, you get a result. Test your water again 2 minutes later and the result is different. So you test again and again until you get a moreless average number. A pain. Now each time I make a test I calibrate the pen but still then it gives me some odd results at times. Lot's of waste of time for a so so reliability.


Hmm I see. Do you have a continuous meter in mind?


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## john6 (23 Mar 2022)

I buy from APC pure, not sure if they deliver to Norway but worth a look.
They are also on ebay and sometimes cheaper than their website.


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## Hanuman (23 Mar 2022)

Hufsa said:


> Ah can you link me this?
> I am located in Norway, so sometimes the options over here are much more expensive, especially shipping from abroad
> 
> 
> Hmm I see. Do you have a continuous meter in mind?


See link I posted above. That's not technically aimed at aquriums but a ph probe is a PH probe. It stores the date in the cloud and you can see your profile. I am pondering buying one myself.


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## john6 (23 Mar 2022)

Hufsa said:


> Hmm I see. Do you have a continuous meter in mind?


I use the Aqua Medic Probe in my reef tank, its as accurate as it needs to be, i calibrate it every 6 months and holds its calibration very well.


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## zozo (23 Mar 2022)

It all depends on what the meter actually is used for, it can be used for a variety of mediums to measure its acidity. And the user manuals are a one size fits all scenario-based upon a worst-case scenario. For example, used in horticulture to measure fertilizer solutions that are highly concentrated (salty) and depending on the target crop that needs to be fertilized it can be rather acidic down to pH 5.0

The glass probe is a semi-permeable membrane (porous glass) and it contains a gelly reference solution with an electrode in it. The meter itself is a voltmeter and it measures the resistance difference between the reference solution and the medium solution. Therefore the probe should be semi-permeable since non-porous glass is an insulator.

The reference solution in the porous probe can get diluted/contaminated over time with the medium that is measured, or dry out if not stored correctly, rendering the meter useless and can no longer be properly calibrated. Depending on the quality of the membrane the lifespan can vary. If used extensively frequent also in relative aggressive mediums it will have a negative impact on the lifespan.  Therefore meters with refillable or replaceable probes are on the market. Also, the refillable probes have an end of life they can get dirty and clog or wear out and get unreliable.

Since the manufacturer of the meter doesn't know what you are going to use the meter for it will always advise on the worst-case scenario regarding maintenance. And using it in a fish tank to measure a tad of fertilized tapwater is far from the worst-case scenario and it will wear out your meter much less...

That's about all I can say about it, can't tell you what to buy nowadays... The market is flushed and the outside of the device never shows the quality. I've used cheap meters that did it pretty good and used expensive ones that did a crapy job. After a while of playing with it, I became rather unsure if the importance of pH in a fish tank is worth investing money in to know it.  IMHO it's not, but this is a personal decision you should make yourself... The opinions in this vary as much as the numbers of meters out there I guess...


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## Hufsa (23 Mar 2022)

Hanuman said:


> See link I posted above.






_cries in wallet_

Are there some good options around the 50-75 euro range?
Even for the Hanna pens I was hoping to spend less.

*I just want some stable CO2 my dudes* 😅


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## Zeus. (23 Mar 2022)

Hufsa said:


> Is this solution just put into the pen or do I need some sort of special container to put the things in? If there is a DIY option I am very interested as the budget is tight


you can put it in the pH pen lid, I do find getting the lid on/off a PITA also, then to leave it in tank 😬 I got the Hanna solution for storage - I should use it more



Hufsa said:


> Which controller would this be?


One I got from CO2 ART-  used as pH pen only ATM


Hufsa said:


> @Hanuman ive got hella BBA and GTA atm and have been religiously taught that the prime suspect is poor CO2.
> So I just want some way of accurately doing a ph profile. Basically I just want to get rid of the algae.
> Are you saying to go for a continous meter / probe instead?


a pH logger would make doing a pH profile easy - even allowing for drift



zozo said:


> It all depends on what the meter actually is used for, it can be used for a variety of mediums to measure its acidity. And the user manuals are a one size fits all scenario-based upon a worst-case scenario. For example, used in horticulture to measure fertilizer solutions that are highly concentrated (salty) and depending on the target crop that needs to be fertilized it can be rather acidic down to pH 5.0
> 
> The glass probe is a semi-permeable membrane (porous glass) and it contains a gelly reference solution with an electrode in it. The meter itself is a voltmeter and it measures the resistance difference between the reference solution and the medium solution. Therefore the probe should be semi-permeable since non-porous glass is an insulator.
> 
> ...


, was going to link you in m8 for your input 

pH pens are a minefield IMHO - I do like the BNC type as you can then choose any BNC probe to use on the unit.


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## Hanuman (23 Mar 2022)

Hufsa said:


> View attachment 184931
> 
> _cries in wallet_
> 
> ...


The PH pen or probe will not provide you a stable CO2. You will.
First look at why your CO2 is not stable. Leaks? Poor circulation and water flow pattern? Proper gas exchange?

All this you can do without a PH Pen.

If you want to get a rough idea of your PH profile at a cheap cost then take a cheap PH pen. Then adjust accordingly.


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## Zeus. (23 Mar 2022)

The drift in a pH pen/probe in 8hrs will be minimal IMO. That's good enough
The next day when redoing profile ignore the pH reading and just log the drift.
I rarely calibrate my probes as I see it as pointless waste of time, just note the drop from degas tank water till lights on and drift from lights on till CO2 off. Then if stable from lights on till CO2 off (I use 0.1pH drift as stable) then what colour is the DC a few hours after lights on (only is stable (ish) pH


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## zozo (23 Mar 2022)

Zeus. said:


> I do like the BNC type as you can then choose any BNC probe to use on the unit.



Over 20 years ago I bought a Hanna GroCheck permanent meter, its manual said the disposable BNC probe should be replaced once a year. I used it for a year then the meter got stored in the shed and actually forgot about it. After about 15 years later I found it back, plugged it in, calibrated it and the darn thing was still working as if it was new.  After that, I still used it for a few years with its original first probe...

Finally, I did put a new after market BNC probe on it and since I had no proper use for it I gave it to a friend with a swimmingpool he's still using it today as far as I know.


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## Hufsa (23 Mar 2022)

Hufsa said:


> For the pH resolution of 0.01 pH to be useful, doesnt accuracy also have to be 0.01?
> If the accuracy is the same on both meters, what is the point of the higher resolution readout?


*Does anyone have an answer to this question?*



Hanuman said:


> The PH pen or probe will not provide you a stable CO2.


Of course not, but it will let me know if I am getting close or not. That is what I want it for. It is a tool for me to be able to do the job of getting CO2 tuned in right. I dont think I have ever said that the ph pen is going to directly give me stable CO2. But it will help me know what is going on.


Hanuman said:


> First look at why your CO2 is not stable. Leaks? Poor circulation and water flow pattern? Proper gas exchange?


I dont actually know if my CO2 is unstable. I have algae, which suggests it. But I dont know for sure. I have already checked for leaks. Circulation and water flow pattern is very good. Gas exchange is quite high and my injection rate is wild especially for a 20 ppm target.


Hanuman said:


> All this you can do without a PH Pen.


I want slightly accurate ph measurements in order to know what's going on. This should not be unreasonable to want



Hanuman said:


> If you want to get a rough idea of your PH profile at a cheap cost then take a cheap PH pen. Then adjust accordingly.


This is why I started the thread. I had questions about which mid range PH pen to go for.


Maybe I am being unfair here but I just wanted some help with my original questions, not to know the theoretical most maximally effective way to measure ph, its way out of my budget. Maybe I should have started with a disclaimer about that, if so I apologise, I will do better. Just getting a bit frustrated if im being honest


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## Wookii (23 Mar 2022)

Hufsa said:


> Does anyone have an answer to this question?





Hufsa said:


> For the pH resolution of 0.01 pH to be useful, doesnt accuracy also have to be 0.01?



Technically no. Meter 1 can have a resolution of 0.01pH, but an accuracy of 0.1pH, and meter 2 a resolution of 0.1pH and an accuracy of 0.1pH.

So for example, say your pH is 6.58pH, meter 1 should report between 6.48pH-6.68pH and meter 2 should report 6.5pH-6.7pH. 0.1pH should be plenty accurate enough for our purposes, but it will depend how deep your OCD runs 

I have this Hanna probe:









						HI-11102 HALO  Glass Body Gel Filled pH Electrode with Bluetooth®
					

No need for a pH meter. Free to use Hanna Lap App for tablet or mobile phone. Flexible, accurate and easy to use.




					www.hannainstruments.co.uk
				




Likely a bit too spendy for the budget you've allocated, but its highly accurate - the most amount of drift I have had over a 6 month period between calibrations is 0.2pH - and has data logging whilst connected to a blu-tooth device,


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## Hanuman (23 Mar 2022)

Hufsa said:


> Maybe I am being unfair here but I just wanted some help with my original questions, not to know the theoretical most maximally effective way to measure ph, its way out of my budget. Maybe I should have started with a disclaimer about that, if so I apologise, I will do better. Just getting a bit frustrated if im being honest


Go for a cheap pen if budget is a the primary concern. See how it goes. It's not like you will use the pen everyday and as said above what you want to know is the drop, not the actual PH. 0.1 will suffice.

As for all the comments you got from me and others they are meant to provide some background/knowledge/experience and perhaps for you to see that not all is black and white, specially when it comes to PH testing. If someone had told me years ago that a probe was a better choice I would not have wasted my time with PH pens.


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## Wookii (23 Mar 2022)

Hufsa said:


> Maybe I am being unfair here but I just wanted some help with my original questions, not to know the theoretical most maximally effective way to measure ph, its way out of my budget. Maybe I should have started with a disclaimer about that, if so I apologise, I will do better. Just getting a bit frustrated if im being honest



Sorry, should have read that last line before posting above - the Hanna pens you have linked to in the OP will do precisely what you want them to, they will allow you to perform a pH profile.

You can also get significantly cheaper ones on Amazon:



			Amazon.co.uk : pH meter
		


Whilst I can't personally vouch for any one of them, most should be sufficiently accurate for you to be able to take measurements for a simple approximate 1pH drop. They just may not be particularly long life products, and won't be of the same order of quality as the Hanna units - like many things in life, with devices like these you often get what you pay for.


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## Hufsa (23 Mar 2022)

Wookii said:


> but it will depend how deep you OCD runs


You know me Wookii, it runs pretty deep but my wallet is shallow 😂

"So for example, say your pH is 6.58pH, meter 1 should report between 6.48pH-6.68pH and meter 2 should report 6.5pH-6.7pH. "
Thanks for this, that was exactly what I wanted to know. I think as long as the budget is what it is then I will go for the 0.1 meter 👍
Get CO2 on point, sell a truckload of plants and then I will revisit the fanciest gadgets down the road 😉



Hanuman said:


> As for all the comments you got from me and others they are meant to provide some background/knowledge/experience and perhaps for you to see that not all is black and white, specially when it comes to PH testing.


I appreciate it Hanuman I really do. I regret not taking a breather before writing that post. Everything is pretty much a shades of gray kind of deal, it is frustrating to me at times, especially when one is trying to find an ok shade of gray to go for and there arent really any absolute best choices.
Im going for the Hanna meter since many of my peers seem happy with it and I think it will do an ok job even if its not perfect 😊


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## JacksonL (23 Mar 2022)

Not sure what they cost over there, but the Hanna PH Checker was the ‘lower’ cost option I went for. I have been very happy with it, it has held calibration well, still checks out after a month of use dialling in CO2.








						Checker® pH Tester with 0.1 pH Resolution - HI98103
					

The HI98103 Checker is the next generation of the original Hanna Checker pH tester. The Checker is the most popular pH meter in the world with over 1 million meters used since its introduction in 1991. From students to researchers, the Checker has been helping people with their pH measurement as...




					hannainst.com.au
				




It’s only 0.1 resolution, not sure if the extra decimal place is essential or not. I haven’t gotten down to , nor needed, that level of fine tuning.


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## KirstyF (23 Mar 2022)

Hey Hufsa

Might be able to solve ur dilemma.

I have a Hana Hi 98103. Been using for 4mths since I had this tank. Very easy to use. Very easy to calibrate. Has done a spot on job for me for full PH profiles and ‘dip checks’.

Lol! The exact pen that JacksonL has just posted. 

I just bought a TDS pen which has PH built in so I don’t really need it any more. Happy to do you a bargain deal on it if ur interested? 

I’ve got the dreaded Covid so might not be able to post til next week but PM me if you are happy with second hand hon and I can take a look at postage costs to Norway etc. 😊


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## JacksonL (23 Mar 2022)

Also it comes with set of 7 buffer, 4 buffer and cleaning fluid but my local horticulture shop had the 250ml bottles of buffers and the storage solution for $7 each. Should last a fair while, only need a drop of storage solution in the cap after each use and the buffer solutions last a while.


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## JacksonL (23 Mar 2022)

KirstyF said:


> Hey Hufsa
> 
> Might be able to solve ur dilemma.
> 
> ...


What timing!


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## KirstyF (23 Mar 2022)

JacksonL said:


> What timing!



Ain’t it just! 😂

@Hufsa Got some mini bottles of buffers too so enough to keep you going for a bit. 😊


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## dw1305 (23 Mar 2022)

Hi all, 


john6 said:


> I use the Aqua Medic Probe in my reef tank, its as accurate as it needs to be, i calibrate it every 6 months and holds its calibration very well.


Salty, heavily buffered solutions will give a reasonably accurate reading with most pH meters, in some ways they just confirm what you already know. With sea water you also have a datum value to aim for. 

The problem with freshwater is that it is a lot less salty and <"a lot more variable">.

cheers Darrel


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## JacksonL (23 Mar 2022)

I know this isn’t the topic of the post, apologies to OP… but with the talk of PH probe technicalities…
Why do I get a relatively instant read when checking calibration in buffer solutions, but it takes a while for the value to stabilise in tank water?


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## Hanuman (24 Mar 2022)

JacksonL said:


> I know this isn’t the topic of the post, apologies to OP… but with the talk of PH probe technicalities…
> Why do I get a relatively instant read when checking calibration in buffer solutions, but it takes a while for the value to stabilise in tank water?


Darrel will be able to explain this from a more technical point of view, but it is because in your tank the PH is constantly shifting due to soil buffering, ferts, co2, low conductivity, water agitation etc while a buffering solution is designed to remain at a very specific PH with the use of acids/salt and bases for you to be able to calibrate the pen/probe.


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## dw1305 (24 Mar 2022)

Hi all,


JacksonL said:


> Why do I get a relatively instant read when checking calibration in buffer solutions, but it takes a while for the value to stabilise in tank water?





Hanuman said:


> low conductivity .................  while a buffering solution is designed to remain at a very specific PH with the use of acids/salt and bases for you to be able to calibrate the pen/probe.


Yes, it is the reasons that @Hanuman says. Buffer solutions are very specific mixtures of <"weak acid / weak base pairs"> and they are fairly "salty" solutions. It is actually the saltiness (conductivity) that is the most important factor in the time that it takes for the <"pH to stabilise">.

If you can find pure sodium chloride (NaCl) you can add that to your water sample, it will <"raise conductivity, but without changing pH"> and the pH will stabilise more quickly.

cheers Darrel


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