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Ph pen recommendation

dw1305

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Hi all,
As title says, any recommendations - appear to be loads on Amazon.Thanks
You need to buy a meter with "2 point calibration" and the buffers (pH4, pH7 and pH10) to calibrate the meter.

Hanna is a good make and I wouldn't spend less than £50 on the meter.

cheers Darrel
 

zozo

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I would say from experience also as Darrel says. buy one form the professional brands like Hana or Milwaukee and one that has a refill option. Tad more expensive but if treated well a once in a life time buy.. The glass probe is permeable and filled with a gel substance. This it uses to compare conductivity between gel and water and calculate the acidity. It never is allowed to be stored dry. It's best to store them with a little destilled water or a damp piece of cotton in the cap. But while storing them and not using for some time it still can dry out. The thing is, if the gel substance in the prode dries/changes in consistancy it can't be properly calibrated anymore.. If it doesn't come with a refill option than it's good for the trashbin. Also experienced cheaper ones having a darn slow reaction time with a still fluctuating value after 10 minutes in the water than you still don't know what the heck is going on. :)
 

zozo

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Either the Hanna 98100 or 98103 are both accurate and easy to use.
I got the 98100 but unsure if you need the .01 PH so if I was to get another I might just get the 98103 and settle for .1 PH reading.
http://www.hannainstruments.co.uk/parameters/ph/testers.html

Seems i'm oldfashion.. :) Refillable is replaced with.
Replaceable Electrode – No need to replace the whole meter when the electrode needs replacing. Spare and replacement electrodes are available for this product.
 

David Edwards

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Either the Hanna 98100 or 98103 are both accurate and easy to use.
I got the 98100 but unsure if you need the .01 PH so if I was to get another I might just get the 98103 and settle for .1 PH reading.
http://www.hannainstruments.co.uk/parameters/ph/testers.html
Hi Andrew,
These look good.
Clicking onto the website it suggests 2 other products to buy, namely combination buffer solution and storage solution - are these essential items - the latter suggests it might be?
Thanks
 

Andrew Butler

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Hi David,
You can't let the tip dry out so you need to put either a few drops of storage solution or PH buffer solution (7 I think) on the tip when you finish.
Buffer solutions you need to calibrate the pen; quite how often I'm not entirely sure, they say every time you use it. Someone else might be better placed to advise you here.
You can use other buffer solutions but I don't know about a good source - hopefully someone can advise you and me both at the same time.
You do get a couple of sachets with the pen to get you started.
 

dw1305

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Hi all,
Clicking onto the website it suggests 2 other products to buy, namely combination buffer solution and storage solution - are these essential items - the latter suggests it might be?
Yes, you need both the buffers and the storage solution.

Storage solution
The storage solution is potassium chloride (4M KCl) and is required because the probes are modified conductivity probes that exchange potassium ions (K+) from the reservoir inside the probe, for an H+ ion (in the water), across an ion selective semi-permeable membrane.

This ion swap generates the voltage that the meter converts into a pH reading. More H+ ions in the water leads to a larger flow of ions and an acidic pH value, fewer H+ ions in the water leads to a lower flow of ions and an alkaline pH.

If you store the probe in RO water, K+ ions will continually leak out of the pH probe. If you store the probe in a strong solution of K+ ions you don't get any leakage. If the membrane dries out it will stop working.

pH buffers
The pH buffers are solutions which consist of an acid and its conjugated base. By altering the proportion of the acid and base you can get a solution with a stable pH, because there is a reserve of un-dissolved compounds, this the "buffer".

<"Phosphate buffers"> are often used, they are mixtures of Na2HPO4 (a base, it has two Na+ ions) and NaH2PO4 (an acid, it has two H+ ions).

Buffering is not entirely straightforward and I've never really found a good way of explaining it. The <"explain stuff - pH page"> is quite good.

cheers Darrel
 

Zeus.

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I agree with Darrel and Zozo and disagree at the same time. You get what you pay for but if you accept the limitations of a cheap pH pen I have found them still useful for doing a pH profile. I got a 0.01 Resolution Digital PH Meter Large LCD Pen Water Quality Tester with Auto Calibration Function and 0.00-14.00 Measurement Range of Amazon £10.00 and find it a very useful tool. Is it accurate :rolleyes: I think not and it is a little slow to get a stable reading, but I just leave it clipped to side of tank and its not too bad.

upload_2018-4-20_19-35-46.png


I dont compare the pH reading from day to day, infact I had to replace the battery recently and I didnt even calibrate it again. But as a quick check to see if the pH is 'stable' what ever the pH reading out is for one photoperiod I think its limitations are acceptable which in turn make them a good buy or better than no pH pen.
 

Zeus.

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The pH pens which Darrel and Zozo mention are in a completely different class OFC. But for £10 you cant go wrong with it IMO (a pH probe for my pH controller cost more than that) But I wouldn't trust the reading form day to day without re-calibrating, I would say there better than not having a pen and what does £10 buy you nowadays anyway.
 

alto

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Except that single point electronic calibration may be yards off & you'd never know unless you check with standards,
there again if you only use a single point standard, imagine any slope (for the curve) that passes though the single point
:D

Only way to know if your pH reading has any validity is by checking calibration standards that encompass your range, & test reading a known solution selected to be midrange

Eg, if you're working pH 7.0 - 6.0
choose pH 4.01 & pH 7.00 calibration buffers, test solution of pH 5.60 (common)
Of course these solutions all have limited shelf life, and are prone to user error (& contamination)

pH probes are subject to (in)accuracy & (im)precision

Most hobby grade probes are pretty shite, Hanna has consistently offered a decent lower level product
 

Angus

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Surely a cheaper probe would do for a PH profile for co2? it might read the wrong PH but it would still read the 1.0 drop? or am i just completely wrong? :)
 

dw1305

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Hi all,
I agree with @alto, pH meters are much more problematic and higher maintenance than people realise.
Surely a cheaper probe would do for a PH profile for co2? it might read the wrong PH but it would still read the 1.0 drop? or am i just completely wrong?
You could be right or wrong.

A lot depends on the composition of the water you are testing. If you have high conductivity water with a lot of carbonate buffering (plenty of H+ ion acceptors), pretty much any pH meter will give you an accurate and consistent reading of about pH 8. You can think of the sea, or Lake Tanganyika, it takes a huge addition of acids (H+ ion donors) to change the pH, because you have a huge buffer of bases (H+ ion acceptors), that will neutralise the acid addition.

The same applies to an acidic solution (one with lots of H+ ion donors), you are going to read consistently below pH4, and you need to add a lot of bases to neutralise the acid.

The problems come because pH is both a ratio, and a log10 scale. When you are looking at the CO2 ~ HCO3- ~ CO3 ~ pH equilibrium you are looking <"at a buffered system with relatively small changes in the amount of H+ ions"> (it is worth reading to the end of the linked thread).

I'm not a CO2 user (there are plenty of ways to accidentally kill your fish, why would you want to add another one?), but if I was I wouldn't be relying on the accuracy of a cheap pH meter to regulate the CO2 levels.

cheers Darrel
 

Zeus.

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Surely a cheaper probe would do for a PH profile for co2? it might read the wrong PH but it would still read the 1.0 drop? or am i just completely wrong? :)

Well thats how I use it, I use the pH reading is just a number not the actual pH, I assume is isnt accurate. I use the DC colour change to get an idea of the level of the [CO2] keeping an eye on the livestock, fish up at the surface its too high so dail back a bit on injection rate. then use that pH reading its just a number after all. Knowing what the actual pH is doesn't help us after all. then I take the readings on a freash run time to hit target pH that gives my pre lights CO2 on time, then does the target pH remain stable for the main part of the photoperiod whilst the CO2 is on.

My pH on my tank ATM via pH controler is 8.22

upload_2018-4-21_9-12-40.png


the starting pH varies day to day being lower just after WC and highest just before WC. Target pH is 6.66 everyday with the pH though the photoperiod varing about 0.1 dependant on light intensity. Thats a pH drop of 1.56 if the pH probe is giving accurate reading which I assume it isnt OFC. But the DC has the same colour change so what does it matter what the actual pH reading says. I do run my tank with a big pH drop to keep the carpet going and it does keep the algea at bay.

After all the general consensus is dont bother with pH controllers ( I only use mine for the getting to the target pH with my duel CO2 injection and PLC setup , but it is OTT) using a constant injection rate gives more stable [CO2] for the photoperiod but doing a pH profile is key to making sure the target pH is reached before lights on and the [CO2] is relatively stable for the first 4-5hours of photo period, which is normally better achieve buy having a higher CO2 injection rate in combination with high surface agitation.

A better pH pen/probe is great, but IMO simular results can be achieved with the cheaper pH pens as long as you take into consideration their inherent limitations and inaccurate pH readings. Taking care not to kill your livestock - after all its only CO2 injected tanks that have CO2 related problems and according to Clive 95% of the problems in CO2 injected tanks are poor CO2 implementation related.
 

zozo

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I tried CO² in aquarium for only 2 years and when the gas ran out never bothered to buy any new gas. I'm to much of a buddhist for CO², not a race car fan, i'm an oldtimer fan. Rather patiently enjoy the ride in a slow pace and gently sway around the complications. The journey is more important than the destination.

But in my vegtable gardening history i collected quite a few pH meters i could play with during this time. Few newly both and a few on the used market, i still have the Milwaukee and the Hanna and a few cheaper brands i don;t rmember what brand they are, total about 5 of them, could be 6 if i do a search.. And each meter has it's issues and limitations by it's own. And funny is even if all calibrated correctly with the very same calibration method still non of them showed the excact same valua measuring a solution that was more than 1 point away from it's calibration point. There always was a deviation in the reading.. Iniminimynimo :rolleyes: and picked the most expensive one and hope it's the most accurate.

Actualy i never gave it much thought about how these things function, it was here at UKAPS i learned that for the first time.. Did some more reading into it and actualy they are awfully simple volt meter devices. I also learned to understand some simple and obvious pH measuring basics that are a bit shrouded in mystery in the general consensus by the users because it's for technical viewpoint and likely other conveniences not fully correctly explained in the manuals.

Since they all have a percantage accuracy deviations is the reason what makes calibration important. The further away you measure from your target calibration the more this deviation obviously will be. Thus it makes sense to take this into account while calibrating.. If you calibrate 7 and your target value is near 4, you will have the maximun deviation the device can give. In this case you should calibrate 4 to have the minimum deviation.Makes sense doesn't it? If for example the inaccuraty is 1% than 1% of 3 is greater than 1% of 0,5. That's relatively simple.

What in this case doesn't make sense is why you always should do a 2 point calibration?. Because the devices accury discrepancy depends on your last calibration target. If your pH target is pH 6.8 than calibrating pH4 doesn't make any sense because you calibrate almost 3 points away from your target. (1% of 3 is greater than 1% of 0,5).

Calibrating is simple resetting the device to it's nearest target. :)

Why even manufacturers still claim you always should do a 2 point calibration to be more accurate is a technical and mathematical mystery to me that probably has more to do with pH4 calibration fluid shelf life. Ph4 is the most unlikely target generaly used, who needs that value anyway if your not Dexter, ore a crop grower that needs pH 5? :rolleyes:
 
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Zeus.

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I tried CO² in aquarium for only 2 years and when the gas ran out never bothered to buy any new gas. I'm to much of a buddhist for CO², not a race car fan, i'm an oldtimer fan. Rather patiently enjoy the ride in a slow pace and gently sway around the complications. The journey is more important than the destination.

But in my vegtable gardening history i collected quite a few pH meters i could play with during this time. Few newly both and a few on the used market, i still have the Milwaukee and the Hanna and a few cheaper brands i don;t rmember what brand they are, total about 5 of them, could be 6 if i do a search.. And each meter has it's issues and limitations by it's own. And funny is even if all calibrated correctly with the very same calibration method still non of them showed the excact same valua measuring a solution that was more than 1 point away from it's calibration point. There always was a deviation in the reading.. Iniminimynimo :rolleyes: and picked the most expensive one and hope it's the most accurate.

Actualy i never gave it much thought about how these things function, it was here at UKAPS i learned that for the first time.. Did some more reading into it and actualy they are awfully simple volt meter devices. I also learned to understand some simple and obvious pH measuring basics that are a bit shrouded in mystery in the general consensus by the users because it's for technical viewpoint and likely other conveniences not fully correctly explained in the manuals.

Since they all have a percantage accuracy deviations is the reason what makes calibration important. The further away you measure from your target calibration the more this deviation obviously will be. Thus it makes sense to take this into account while calibrating.. If you calibrate 7 and your target value is near 4, you will have the maximun deviation the device can give. In this case you should calibrate 4 to have the minimum deviation.Makes sense doesn't it? If for example the inaccuraty is 1% than 1% of 3 is greater than 1% of 0,5. That's relatively simple.

What in this case doesn't make sense is why you always should do a 2 point calibration?. Because the devices accury discrepancy depends on your last calibration target. If your pH target is pH 6.8 than calibrating pH4 doesn't make any sense because you calibrate almost 3 points away from your target. (1% of 3 is greater than 1% of 0,5).

Calibrating is simple resetting the device to it's nearest target. :)

Why even manufacturers still claim you always should do a 2 point calibration to be more accurate is a technical and mathematical mystery to me that probably has more to do with pH4 calibration fluid shelf life. Ph4 is the most unlikely target generaly used, who needs that value anyway if your not Dexter, ore a crop grower that needs pH 5? :rolleyes:

Yes agree 100%, the calibrating the pH in the range being used is the best by to be close within that range your measuring, if you what the reading to be close to what it actually is. I have one pen one controller calibrate them both with same buffers and there fine at the buffers PH ( pH4 and pH7.0) but inbetween there close but not the same reading. Hence I use the reading as a number not the actual pH

In my car same as all the spedo isnt accurate, but I use a GPS unit to get the actual speed and then set my cruise control or speed limiter to the speed I am happy with - normally GPS speed is about 10% lower than speedo speed ( I use the term speed loosely as its is velocity that the GPS gives as far as I'm aware)
 

Angus

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Great reading guys thank you kindly for the in depth replies.

i have always just used a drop checker with 4dkh in my co2 tanks never owned a ph pen.

Since coming back to the hobby i am trying to perfect non-co2 growing in a moderate to high lighting tank, its going fine in the tank with lots of stems and hungry plants but the tank without a fast uptake of nutrients is struggling currently with algae, which doesn't surprise me all that much.

Thanks again for the lessons guys.

Sent from my E2303 using Tapatalk
 
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Zeus.

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Thanks again for the lessons guys.

I dont see them as lessons its sharing info, you post what you have learnt or your assumptions from your reading and if your post is incorrect an expert with a greater depth of understanding corrects you. So we all learn/share together Standing on the shoulders of giants eg T Amano, T Barr, etc
 
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