Ranking of best pH meters, April 2016

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Ranking of best pH meters, April 2016

Post by bekateen » Sun Apr 17, 2016 7:55 am

Thanks to @ridout for the link: https://wiki.ezvid.com/best-ph-testers.

Cheers, Eric

P.S., This is similar to another thread, Is there a digital TDS meter you would recommend?
Last edited by bekateen on Sun Apr 17, 2016 4:55 pm, edited 1 time in total.

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Re: Ranking of best pH meters, April 2016

Post by TwoTankAmin » Sun Apr 17, 2016 3:55 pm

I wish there was one of these for continuous monitoring devices. I burned through two testers in 3 months. I then tried an inexpensive Chinese made monitor, twice, and both were returned to the sellers as crap. I finally, found an outfit in Australia that made the unit I have been using for the past few years.

Once put into use, the pH sensor on a pen type meter must be kept in a solution when not in use. If the sensor is allowed to dry out, its becomes useless and must be replaced. My in tank monitor can only dry out if the tank leaks to below the level it is at in the tank.

I also found the units the sell for $30 or $40 can be flakey. They are almost useless for doing fine adjustments when one is batching replacement water as one adds ingredients.Where they are most useful is for acid water because they can measure levels the reagent kits typical in the hobby cannot. The pen testers seem to need recalibrating more often than my continuous monitor. Depending on one's application needs, continuous monitors are often the better option, but they are also much more expensive. The only hand held tester I use now is one which read TDS and temperature in C. I have a homemade chart on the wall in one room which shows the F value of C in .5 increments.

Interestingly, when I was using the tester I did some test comparisons of results to my API low range kit and the readings from the pen tester and the kit agreed in most instances. My problem with the kits was I needed to read pH in the low 4 range and the kits won't do this.

As an fyi, the tester I used and abandoned was the Hanna pHep unit http://hannainst.com/hi98107-phep-ph-tester.html
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Re: Ranking of best pH meters, April 2016

Post by dw1305 » Mon Apr 18, 2016 3:27 pm

Hi all,
The problem with pH meters is really the same as the problems with pH as a measurement. The accuracy and validity of the value you record depends upon the carbonate hardness and conductivity of the water you test.

If your water is alkaline, and has high conductivity, then pH is a stable value and nearly all pH meters, or pH test kits, will give you a reasonably accurate result.

If your water is soft, and has low conductivity, then pH is inherently unstable, less biologically meaningful and much more difficult to measure.

There is a summary of the technical problems in low conductivity water here: "pH Probes for Pure Water Applications": <http://www.hach.com/asset-get.download- ... 4140868050>.
TwoTankAmin wrote:The only hand held tester I use now is one which read TDS and temperature in C. I have a homemade chart on the wall in one room which shows the F value of C in .5 increments.
I do the same as TTA, I only use a conductivity meter and even then only occasionally.

I started looking for dip meters, or simple colormetric test, that gave you a relatively consistent result across a range of water conditions, but I couldn't find one for a lot of the parameters (NO3-, pH, PO4---, Dissolved Oxygen) that were of interest to us. I have access to the staff and equipment for an analytical lab., and I could compare the values I got from the test kits and meters with the values that the analytical staff, using standard analytical techniques, generated.

Using fresh water samples over a whole spectrum of nutrient, hardness and ppm "TDS" value the only cheap meter, or test, that you could just dip in, and it would give you accurate and repeatable values, was a conductivity meter. It wasn't the parameter that you would have wanted, but it was the one that worked.

cheers Darrel

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Re: Ranking of best pH meters, April 2016

Post by 2wheelsx2 » Mon Apr 18, 2016 5:07 pm

My wife works as a full time chemist in a massive research facility and she always laughs at me when I read the pH on my monitors. She's like, you know on those meters that you can afford, the decimals places are almost meaningless right? She told me the regular titration kits are actually more consistent from reading to reading.

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Re: Ranking of best pH meters, April 2016

Post by ridout » Mon Apr 18, 2016 8:24 pm

I had recently bought a ph pen as i was just interested in seeing what the "true" ph of my water (rain water) actually was. In reading these comment had made me feel ten thousand times better as i almost had a heart attack seeing 4.5 on my "new £13 ph pen" that was obviously a buy on soooo many grounds. I thought i was doing the right thing buying it as i have never been one for testing my water. I must confess to using a TDS pen for the past year which has been my go to item when seeing fish trapping or generally taking mindful notes to see if i can bring the TDS down a little to help spur things on in my tanks. Now am i write to be trusting my TDS pen or have been fooling myself for the past year?

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Re: Ranking of best pH meters, April 2016

Post by dw1305 » Mon Apr 18, 2016 9:47 pm

Hi all,
2wheelsx2 wrote:My wife works as a full time chemist in a massive research facility and she always laughs at me when I read the pH on my monitors. She's like, you know on those meters that you can afford, the decimals places are almost meaningless right? She told me the regular titration kits are actually more consistent from reading to reading.
Weak acid/weak base titration would be better, but deciding where the "end point" is is still subjective <http://www.chemguide.co.uk/physical/aci ... urves.html>.
ridout wrote:I had recently bought a ph pen as i was just interested in seeing what the "true" ph of my water (rain water) actually was. In reading these comment had made me feel ten thousand times better as i almost had a heart attack seeing 4.5 on my "new £13 ph pen" that was obviously a buy on soooo many grounds. I thought i was doing the right thing buying it as i have never been one for testing my water. I must confess to using a TDS pen for the past year which has been my go to item when seeing fish trapping or generally taking mindful notes to see if i can bring the TDS down a little to help spur things on in my tanks. Now am i write to be trusting my TDS pen or have been fooling myself for the past year?
TDS meters measure conductivity, and even cheap meters give you a fairly accurate reading. I've found that in the winter the conductivity of our rain-water reads down to about 30 microS (20 ppm TDS) and up to over 100 microS in the summer (presumably from atmospheric dust).

As we are quite near neighbours you'll probably find your rain-water has enough carbonate buffering to read pH~7.8, if it was pure H2O it would read about pH6, but it would be very difficult to get a stable reading without a "pure water pH" meter. I can take a water sample into the lab. but if the conductivity is really low then pH is always going to be a "movable feast".

cheers Darrel

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Re: Ranking of best pH meters, April 2016

Post by bekateen » Mon Apr 18, 2016 10:20 pm

dw1305 wrote:The problem with pH meters is really the same as the problems with pH as a measurement. The accuracy and validity of the value you record depends upon the carbonate hardness and conductivity of the water you test.

If your water is alkaline, and has high conductivity, then pH is a stable value and nearly all pH meters, or pH test kits, will give you a reasonably accurate result.

If your water is soft, and has low conductivity, then pH is inherently unstable, less biologically meaningful and much more difficult to measure.
Darrell,

From what you're saying, a pH meter is still useful for people with water that is relatively hard, correct? And in that case, perhaps most pH meters (cheap and expensive alike) will give reliable readings. But then the issue is durability: How long will the device last with proper maintenance?


My municipal tapwater is rated as "moderately hard" according to local city publications, conductivity around 250-500, depending on time of year and water source (our city gets water from several nearby wells and also buys water from other water utilities, including ones relying on river sources and snow melt: highly variable). And after adding Seachem Prime to neutralize chloramines, my conductivity jumps to the 350-450 range (higher if tapwater is high to start with). Then when added to the aquarium, organics already in the aquarium can easily bump the conductivity up to 800 in some of my tanks, and it climbs (for obvious reasons) the longer I go between water changes.

I still worry most about the conductivity readings of my aquaria, but I find it useful to check pH too. My banjos don't breed when the pH is high, even if the conductivity is stable. But as pH drifts down into the 6 range, and as low as 4.5, the banjos spawn.

But to your point about pH reading reliability, I sometimes have to leave the pH probe in the aquarium for up to 5-10 minutes to get the pH reading to stabilize; I've always assumed that meant the tank is not a strongly buffered aquarium. Is that correct? If not that, what else would lead to really slow equilibration?

Cheers, Eric

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Re: Ranking of best pH meters, April 2016

Post by dw1305 » Tue Apr 19, 2016 4:39 am

Hi all,
bekateen wrote:From what you're saying, a pH meter is still useful for people with water that is relatively hard, correct? And in that case, perhaps most pH meters (cheap and expensive alike) will give reliable readings. But then the issue is durability: How long will the device last with proper maintenance?

My municipal tapwater is rated as "moderately hard" according to local city publications, conductivity around 250-500, depending on time of year and water source (our city gets water from several nearby wells and also buys water from other water utilities, including ones relying on river sources and snow melt: highly variable). And after adding Seachem Prime to neutralize chloramines, my conductivity jumps to the 350-450 range (higher if tapwater is high to start with). Then when added to the aquarium, organics already in the aquarium can easily bump the conductivity up to 800 in some of my tanks, and it climbs (for obvious reasons) the longer I go between water changes.

I still worry most about the conductivity readings of my aquaria, but I find it useful to check pH too. My banjos don't breed when the pH is high, even if the conductivity is stable. But as pH drifts down into the 6 range, and as low as 4.5, the banjos spawn.

But to your point about pH reading reliability, I sometimes have to leave the pH probe in the aquarium for up to 5-10 minutes to get the pH reading to stabilize; I've always assumed that meant the tank is not a strongly buffered aquarium. Is that correct? If not that, what else would lead to really slow equilibration?
Unfortunately pH meters are quite high maintenance bits of kit. The electrodes often have a limited life (they exchange K+ ions in use), even when they are stored in 4M KCl etc when not in use. <http://www.coleparmer.co.uk/TechLibraryArticle/684>. ISFET meters are lower maintenance, you store them dry, but they are quite expensive.

The meter really need buffering before use, and you have to buy the buffers.The meter should be turned on for ~10 minutes before you use it

Buffered alkaline water will give you an accurate pH using most methods, and so would really acid water. Soluble salts and acids will both raise conductivity because you have more ions in solution (H+ ions for acids).

Salts can be either alkaline (H+ ion acceptors), neutral or acidic (H+ ion donors). A neutral salt like KCl ("If an ion derives from a strong acid or base, it will not affect the acidity of the solution") raises conductivity, but doesn't change pH.

Certainly for some fish conductivity isn't important and low pH allows them to breed successfully even at high conductivity levels.

Equilibrium takes longer to reach in low conductivity solutions, or when you use gel filled electrodes.

cheers Darrel

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Re: Ranking of best pH meters, April 2016

Post by bekateen » Tue Apr 19, 2016 4:49 am

Thanks Darrel,

When I bought my conductivity meter last year, I also bought the calibration buffers, storage buffer, and washing solution.. Yep, the costs add up. My conductivity meter is a combined conductivity/pH/temp so that's nice, but obviously if one part breaks I probably lose the whole thing... Time will tell.

Cheers, Eric

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Re: Ranking of best pH meters, April 2016

Post by dw1305 » Tue Apr 19, 2016 9:48 am

Hi all,
bekateen wrote:When I bought my conductivity meter last year, I also bought the calibration buffers, storage buffer, and washing solution.. Yep, the costs add up. My conductivity meter is a combined conductivity/pH/temp so that's nice, but obviously if one part breaks I probably lose the whole thing... Time will tell.
I'm pretty sure all the "HI 991300" TDS/pH meters mentioned in your "Is there a digital TDS meter.....:http://www.planetcatfish.com/forum/view ... =4&t=41899" thread are still working.
dw1305 wrote:.......I'm not as keen on the combined pH/Conductivity meters, but we've recently bought a few "HI 991300" combined meters (~£400), but we haven't had them long enough to pass any comment on their reliability. ..... The reason I don't like combined meters is that pH meters are quite high maintenance and I would estimate that we get through 2 or 3 pH meters for every conductivity meter we buy.
cheers Darrel

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Re: Ranking of best pH meters, April 2016

Post by bekateen » Tue Apr 19, 2016 1:35 pm

I bought the HI98129. Actually I did have trouble with it a day or two ago, my most recent usage, and I currently have an email in to tech support.

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Re: Ranking of best pH meters, April 2016

Post by nelieto060 » Mon Mar 20, 2017 8:49 am

I have use Dr.meter S30 3-in-1 Soil pH Meter. It is really good for ph measurement. I have use this one for my garden soil. It always help me to keep my garden pH level. It also measures the moisture level of soil.

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Re: Ranking of best pH meters, April 2016

Post by RBjerrum » Tue Aug 15, 2017 10:32 am

I've been using the Horiba LAQUAtwin pH33 meter lately. It's quite expensive but if you want accurate readings its the way to go. It allows you to test water by just lowering the meter in the water, or by dropping a few drops of the liquid onto the meter.
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Re: Ranking of best pH meters, April 2016

Post by TwoTankAmin » Wed Aug 16, 2017 12:32 pm

I am curious if people are also using any continuous monitoring of parameters as opposed to spot testing. What I wonder is if they see any difference between the accuracy and reliability of the two different types of device?

I started with inexpensive testers and found that the pH ones went south in a matter of months. On the other hand my continuous monitor which reads temp./TDS or conductivity/pH has been quite reliable for the three or so years I have had it in operation. In my case things are complicated because it is used on a tank with "tea stained" water. I find that I have to clean the probes regularly. I also find I need to recalibrate the pH part about every 2 months, perhaps a bit less.

The monitor I use is not scientific grade. It is used primarily (but is not limited to) hydroponic applications.
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