I was wondering about further automating my pool's chemistry. Are automated ph meters considered reasonably reliable? Any things to watch out for? My ultimate goal is to build some kind of chemistry monitoring setup (probably controlled with an Arduino or similar), that can let me track how levels vary under different conditions. For this I will need to get some sensors and it would be useful to know what the consensus is on reliability and possible pitfalls. Thanks!
How good are electronic ph meters?
- Thread starter nutria
- Start date
- May 23, 2015
- 24,379
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
pH probes work just fine. ORP probes for FC are not very useful as their sensitivity is degraded by CYA. Amperometric probes for chlorine exist but they are prohibitively expensive (~$3000+ for a probe and meter). There are no probes for measuring TA, CH or CYA.
All electronic systems need regular calibration and PM as well as probe replacement. Is it really worth thousands of dollars in equipment, countless hours programming and debugging a PLC and the time & expense of maintaining the setup to automate data collection? I can tell you that any precision gained by the setup will not make any difference in how you will maintain the pool.
Just my opinion.
All electronic systems need regular calibration and PM as well as probe replacement. Is it really worth thousands of dollars in equipment, countless hours programming and debugging a PLC and the time & expense of maintaining the setup to automate data collection? I can tell you that any precision gained by the setup will not make any difference in how you will maintain the pool.
Just my opinion.
That sounds accurate ^^^ but if it's a hobby whatever floats your boat... you may come up with the next best thing
Haha, you are absolutely right, t certainly would not be worth it if it cost thousands of dollars, not for me anyway. However, I expect that an arduino plus some probes should cost on the order of $100 rather than $1000. As for spending the time and effort, this is a fun project for me, more of a hobby than a necessity. I am an experimental physicist by day, so these things are sort of bread and butter, though not chemical sensors per se. Also, I understand the precision won't improve in any noticeable way how well the pool is taken care of. Anyway, I understand from your answer that the ph meters are generally considered reliable and useful rather than a can of worms like the ORPs. Thanks!
I use pH meters for things other than the pool, and as has been mentioned they do require frequent calibration with calibration reference fluid, so more trouble than they are worth vs using a pH test block with pool water.
Jaimslaw
LifeTime Supporter
The use of a PH meter is something that either fits with one's profile or it doesn't. My take...there are all sorts of testing steps that consume one's time, so its a matter of whether the time to do an occasional calibration step (a two minute affair) and placing the probe in the pool sample and awaiting the ph reading is that much of an imposition on one's time.
I do it only every once in a while, e.g., when I have some in between, ambiguous color readings. I also find it helpful to use the PH meter since I hover around the 7.6+ level to address PH creep, and don't want it to be a misread that pushes it higher than that. I guess one could call it a hassle to use a PH meter, but that's a somewhat subjective opinion with much disparity as between ppl. Me, I find the geek factor outweighs the little extra time it takes. Also, having purchased several of the under $45 meters just for experimentation reasons (and that all important geek factor), I found them surprising accurate. It would only rise to the level of a necessity if one is doing a lot of hand wringing over whether they are reading the PH color block correctly. Some ppl do have this issue and ph meters can have a reassuring impact (noting here that use of these meters, including calibration, is not a splitting of the atom exercise, as some in previous posts have made it out to be).
I do it only every once in a while, e.g., when I have some in between, ambiguous color readings. I also find it helpful to use the PH meter since I hover around the 7.6+ level to address PH creep, and don't want it to be a misread that pushes it higher than that. I guess one could call it a hassle to use a PH meter, but that's a somewhat subjective opinion with much disparity as between ppl. Me, I find the geek factor outweighs the little extra time it takes. Also, having purchased several of the under $45 meters just for experimentation reasons (and that all important geek factor), I found them surprising accurate. It would only rise to the level of a necessity if one is doing a lot of hand wringing over whether they are reading the PH color block correctly. Some ppl do have this issue and ph meters can have a reassuring impact (noting here that use of these meters, including calibration, is not a splitting of the atom exercise, as some in previous posts have made it out to be).
My point above is that unless you are trying to carefully manage CSI due to high CH levels or have similar situation that the acceptable pH range for a pool is fairly high, generally 7.5 - 7.8 So you really don't need a pH meter reading to .01, that range is easy to achieve with the simple color comparitor block within +/- .1 Vs keeping a pH probe moist in a low pH solution constantly and free of contamination, rinsing with deionized water, plus running 2 point calibrations against reference fluids, rinsing and drying between the steps to prevent cross contamination,, a step which many manufactures suggest should be done weekly for non precision readings (some may say monthly), and before each test for precision testing. Is all that really worth it for a pool where you will likely only test pH a couple of times per week. Don't get me wrong pH meters are great when you need to do a dozen or more pH testings per day, and when you need to test to higher precision or over a wider range than a pool test block allows.
Jaimslaw
LifeTime Supporter
A reading of all the threads about PH meters makes evident that there are those who push back against the meters and those that have a more accepting opinion of meters. Fairly consistent in all of the pro and con posts is the consensus that one does not need a PH meter. Proponents do make the case that it can be a helpful tool. We can all use help on occasion with things. This particularly is the case for a large number of the posters who have expressed that reading of the ph color block is something that poses some difficulties that most of us do not experience. PH meters has served a useful purpose for those ppl. For others, the use of the ph meter has not risen to a level of inconvenience..just one in a battery of tests that we subject our pools to.
Thanks for the well balanced response. I was just asking for what level of reliability one can expect, not proposing that one does not use the traditional method or that one is better than the other. I am not sure why there is so much push back on the automation questions of this type. Most of these tests have problems of some type, be it reagents aging, calibration issues, etc. Not one tool is perfect, but I happen to think that continuous or nearly-continuous monitoring of levels is something that I would find useful (and somewhat entertaining!).
- May 23, 2015
- 24,379
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Not so much push back just a reality-check.
If you are jazzed about setting up a continuos monitoring system for your pool, go for it! It would be an interesting build thread to read and I'm sure you'd get lots of interested participants.
The reality of pool automation systems is dodgy at best. For example, Pentair sells their IntelliChem system (pH and ORP FC control) as well as the IntelliPH System (pH control only). You can Search TFP for ORP articles but what you find, in a nutshell, is that they are incredibly finicky and difficult to get working because ORP is sensitive to so many different water parameters that it is effectively useless. Worse, it makes the pool owner spend inordinate amounts of time constantly fiddling with the control system that, to many, it just seems totally pointless. By contrast, because pH monitoring and control is so much simpler, the IntelliPH systems are fairly bullet-proof in operation and most owners of them love to have the automated pH control. The downside to the IntelliPH systems are that the peristaltic pumps have very short lives (only about a year or so before they corrode) and sometimes you get a bad pH probe and the system dumps all of the acid into your pool.
So, in theory, control and monitoring systems are great! In practice, they still leave a lot to be desired. But if you want to play with setting up a monitoring system, as I said, go for it.
I'm generally not in favor of pH meters, but in your case it sounds more along the lines of an interesting project to develop your own monitoring set up for curiosity sake and probably learn a whole lot in the process. GO for it!
pH sensors and meters do require frequent calibration checks so be prepared with some standard pH solutions, usually available at 4.0, 7.0, 10.0 or other increments to verify your pH meter. Probably a 7.0 would be enough for your purposes.
I don't have much experience with ORP sensors or their calibration, but with any electronic sensor, being able to verify calibration is essential if you're going to use the data to make decisions. That being said, just getting it set up and working would be a learning experience, then work on how robust and accurate the system can be.
pH sensors and meters do require frequent calibration checks so be prepared with some standard pH solutions, usually available at 4.0, 7.0, 10.0 or other increments to verify your pH meter. Probably a 7.0 would be enough for your purposes.
I don't have much experience with ORP sensors or their calibration, but with any electronic sensor, being able to verify calibration is essential if you're going to use the data to make decisions. That being said, just getting it set up and working would be a learning experience, then work on how robust and accurate the system can be.
I am not against eletronic pH monitoring as I said above, I just stated what I feel is an honest review of the amount of time that one needs to spend calibrating them. How often this needs to be done in an automation system constantly in contact with pool water, I don't know. I do know that at least one pH automation system skips using them entirely and instead uses a system that is basically pH test strips on an automatic spool with a colormetric sensor and a solenoid valve to allow sampling every X number of hours.
I did read about the existing automated systems and questions posted about them and I saw that the chlorine measurements were problematic, but as you say, the ph ones appear to be reasonable and well integrated into existing systems. Now, I have no intention of buying a Pentair (or other) prebuilt automation system, but I thought that the existence of ph automation that works well is a good indication that those sensors are reliable. You say it is a reality check, but it seems that a question specifically about ph meters prompted a number of people to actively discourage use of ph automation and used ORPs as example of why they would not work reliably ... it sounded like pushback to me.
Anyway, also lots of good feedback, so eventually I will get to putting something like this in my pool for my own amusement and if I do I will make sure to post how it goes.
I supply and use industrial pH meters. These are high end online instruments. Generally the users of these instruments calibrate them monthly. I would imagine that on lower end pool systems you could get by with that same schedule.
I think the great concern most of us have about these systems is two fold, first if the owner will keep up with calibration requirements, and second is them going crazy either through sensor failure, pump failure or other means and dumping the entire tank of acid into the pool at once.
I totally get that. In fact my initial idea is not to build an automated dispenser but rather and automated logger, the dispensing will be done manually. If I monitor ph constantly, after a little while, I know what I expect to see and can point check against the usual method. After a few weeks/months of doing this one can see whether the ph probe is doing what is expected and whether factors such as temperature, other chemical levels, etc affect its readings. If the probe starts deviating too much from the trends it should be reasonably easy to see. Setting up a dispenser system that will deliver acid based on those readings is an addition to such a project. If I was to think about automatic dispensing I would probably add additional sensors (from a different batch, etc) and do some kind of majority voting or any of the other methods to increase reliability.
- - - Updated - - -
Sounds reasonable. Thanks for the info, that is very useful.
- May 23, 2015
- 24,379
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Sorry if you felt like it was push-back. Your original post included the following statement -
I took that to mean your intention was to build a comprehensive system for measuring temperature, pH and FC (as I said, TA, CH and CYA cannot be automated). My initial response mentioned ORP because that is the kind of FC monitoring probe you could get easily on the retail market and for a relatively cheap price (ORP probes retail for ~$200-$300). For the majority of pool owners, automated chemical monitoring is really not at all necessary and represents an added complexity that just makes pool ownership harder, not easier. So, while it is often sold by breathless salesman as a "thing" that every pool owner "must" have, the experiences shared hear on TFP tell the opposite story. Being new to the site, I wanted to make sure you had a healthy dose of skepticism so that you were prepared for the realities of automation control.
One of the reasons why we ask people to put in some personal details about themselves (location, occupation, hobbies, etc) is to get a feel for where they are at in life. TFP membership represents the very broad spectrum of backgrounds, occupations, interests and experience. So, since you say that you're an experimental physicist (do you teach in academia or work in industry? I was materials scientist & engineer in a former life and worked many years in the semiconductor processing industry), I think this type of project is right up your alley if you have the time and money to spend on it.
Best of luck,
Matt
Put like that I see why you thought I was asking more than I was. The previous sentence specifically mentions ph meters and that is what I am currently aiming for. There is indeed a lot of information on the site about the problems with ORP meters but when it comes to ph, it was not so clear to me. As someone has mentioned there are ph automated systems that appear to work well, but often the questions about them get lumped in or mixed up with discussion of the unreliability of ORP. What I want to do is *further* automate my pool, not fully automate. My first step was installing a SWCG and I am very happy with that. My second step is to keep track of the ph drift as this is what is currently taking my time.
Yes, I get that personal details can help people give a response. I am not a big fan of putting too much information up front in a public forum. For this purpose suffice to say that I have a phd in experimental physics and have spent most of the last 12 years in labs doing several flavors of data acquisition, but I have no experience with chemical measurements
If you are just looking for pH logging and not a do it yourself project check out the various pH measuring systems sold to the hydroponics industry, the biggest name brand you are likely to find is Hanna.
Jaimslaw
LifeTime Supporter
I thought it might be informative to comment on the subject of calibration of PH meters, as there are some misconceptions about this process.
Calibration comes in two flavors: the first being maximum preciseness in calibration, the other being acceptable preciseness for the intended purpose. As explained below, which method you choose will determine the time incurred in calibrating the meter. For pools, you need not go the maximum preciseness calibration method.
By way of background, PH meters are used extensively by beer brewers and by aquarium owners. Forums exist for each of these past times, where the subject of PH meters gets a lot of traffic. The reason for this is that PH levels that are even slightly off can have devastating effect...entire batches of brew can go bad and hundred of dollars (thousands even) in fish can go belly up when PH is off nominal levels. Moreover, precise readings are needed to guage whether PH may be increasing or declining, as just a few hours (e.g. 12 hrs) of an unknown increasing or decreasing PH level can lead to adverse, costly losses or bad brew batches. So these ppl are rather fanatic about getting accurate PH results, and consequently, conduct two point calibrations (calibrating at ph ~4.0 and again at ~7.0). Another reason for conducting these two calibrations: beer brews need to come in at the much lower 4.0 ph range - something pool owners do not concern themselves with.
My research and personal experimentation with as many as 4 different ph meters makes it evident that pool owners can skip the 4.0 calibration step, as there will be no testing in that low ph range. This is not to say that the meter will be as accurately calibrated with a one point calibration ste as with a two point step. It won't be. But it will be plenty accurate for testing in the 7.0 range for us pool owners.
I calibrate every time I use my meter...not so much because I need to, but because it is not a time consuming endeavor. I keep my meters in a small cup with 4.0 solution for longevity, which involves no more time than placing it in the solution when done. Calibration is no less a hassle. I keep a bottle of premixed solution of 7.0 fluid handy, pour a little in a plastic cup, place my meter in it; and after about a minute, make any necessary PH calibration adjustment with a tiny screw driver. I then take it out if the solution, pour some distilled water on the tip, blow off excess water and place it in my cup with pool water. That's it. After the PH reading is taken, I simply rinse it off again and place it into my 4.0 storage solution cup. All of this is a two minute affair, so it does irk me a little when this is characterized as some laborious, time consuming process. Really? Two minutes?
Anyways, I did spend a lot of time experiemnting with different meters, using the meters as a way to "calibrate" the color readings on varous PH color blocks, and just enjoying myself the whole time. But I did learn a lot from those brewing and acquarium forums about Ph meters, calibration, etc. which I also enjoyed doing.
What I did learn is that these PH meters are remarkedly accurate - even some of the cheaper models beat out some of the meters that cost three times or more as much.
Because it requires only a few bucks and a few more minutes of your day, I will always wonder why its necessary to attempt to talk someone out of another PH testing method on the basis of the time involved. Heck, the geek factor alone is wOrth it.
IMO, asserting that PH meter testing is ill advised because of the time involved reminds me of the adage about how the night lamp post serves the town drunkard....i.e., he uses it more for support than illumnination. Anyways, I hope the foregoing sheds some light on the PH meter issue.
Calibration comes in two flavors: the first being maximum preciseness in calibration, the other being acceptable preciseness for the intended purpose. As explained below, which method you choose will determine the time incurred in calibrating the meter. For pools, you need not go the maximum preciseness calibration method.
By way of background, PH meters are used extensively by beer brewers and by aquarium owners. Forums exist for each of these past times, where the subject of PH meters gets a lot of traffic. The reason for this is that PH levels that are even slightly off can have devastating effect...entire batches of brew can go bad and hundred of dollars (thousands even) in fish can go belly up when PH is off nominal levels. Moreover, precise readings are needed to guage whether PH may be increasing or declining, as just a few hours (e.g. 12 hrs) of an unknown increasing or decreasing PH level can lead to adverse, costly losses or bad brew batches. So these ppl are rather fanatic about getting accurate PH results, and consequently, conduct two point calibrations (calibrating at ph ~4.0 and again at ~7.0). Another reason for conducting these two calibrations: beer brews need to come in at the much lower 4.0 ph range - something pool owners do not concern themselves with.
My research and personal experimentation with as many as 4 different ph meters makes it evident that pool owners can skip the 4.0 calibration step, as there will be no testing in that low ph range. This is not to say that the meter will be as accurately calibrated with a one point calibration ste as with a two point step. It won't be. But it will be plenty accurate for testing in the 7.0 range for us pool owners.
I calibrate every time I use my meter...not so much because I need to, but because it is not a time consuming endeavor. I keep my meters in a small cup with 4.0 solution for longevity, which involves no more time than placing it in the solution when done. Calibration is no less a hassle. I keep a bottle of premixed solution of 7.0 fluid handy, pour a little in a plastic cup, place my meter in it; and after about a minute, make any necessary PH calibration adjustment with a tiny screw driver. I then take it out if the solution, pour some distilled water on the tip, blow off excess water and place it in my cup with pool water. That's it. After the PH reading is taken, I simply rinse it off again and place it into my 4.0 storage solution cup. All of this is a two minute affair, so it does irk me a little when this is characterized as some laborious, time consuming process. Really? Two minutes?
Anyways, I did spend a lot of time experiemnting with different meters, using the meters as a way to "calibrate" the color readings on varous PH color blocks, and just enjoying myself the whole time. But I did learn a lot from those brewing and acquarium forums about Ph meters, calibration, etc. which I also enjoyed doing.
What I did learn is that these PH meters are remarkedly accurate - even some of the cheaper models beat out some of the meters that cost three times or more as much.
Because it requires only a few bucks and a few more minutes of your day, I will always wonder why its necessary to attempt to talk someone out of another PH testing method on the basis of the time involved. Heck, the geek factor alone is wOrth it.
IMO, asserting that PH meter testing is ill advised because of the time involved reminds me of the adage about how the night lamp post serves the town drunkard....i.e., he uses it more for support than illumnination. Anyways, I hope the foregoing sheds some light on the PH meter issue.