# pH Pen vs. pH Monitor



## NotoriousENG (19 Nov 2021)

Hey Everyone,

I am getting tired of guessing at my co2 so think it's time to get a digital pH meter of some sort. I'm contemplating getting one of the probe-style pH monitors (like a Milwaukee) since I've heard they are more accurate and last longer. So my question is if y'all think the monitor is worth it over a pen-style meter. If I do go the monitor route, I will probably get one that's also a pH controller since the price difference seems to be marginal. I don't know if I would use the controller aspect but for a few extra dollars, it seems worth having the option.


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## zozo (19 Nov 2021)

I've used a controller for quite some time and they work pretty good as pH monitors... But you should only use the controller as a fail-safe in case of a CO² tank dump. Thus that it cuts the CO² off when it shoots down to a dangerous pH level. Then you still need a pretty accurate and stable regulator and needle valve to get to the required stable BPS to stay in the safe pH range.

In general consensus, it's said a dual-stage regulator also should prevent a tank dump, so everybody takes it for granted. But if you get to this point and it doesn't it'll be too late. And this point is reached at a near-empty CO² tank.

What I personally find questionable about permanent pH monitoring is, a pH meter is a voltage meter and via the probe, the tank water is constantly grounded to the electrical grid. And there will constantly flow an electrical current through the aquarium. All other electrical equipment in and around the aquarium also spreads an inductive current and every body of water has a capacitive property. A body of water in a glass tank that is insulated and not grounded will have no electrical current running through it. Once it is grounded it will have a current running through it. Depending on the severity of this current fish can be affected and irritated by it.

There is some controversy to it, in how far fish are affected and this is never fully scientifically investigated.  Some say you always should ground the aquarium water for your own safety and therefore Titanium ground pins are available in the trade, others say you definitively should not for your fish safety and steer away from it.

I tend towards the group that steers away from it... Referring to an old school issue from back in the day where everybody used tube lights and Ballasts, it was said from experience never to switch on all lights at once because the sudden light flash startles and stresses the fish. But this theory didn't seem to be very true since lots of us use LED nowadays and switch on lights suddenly, some even use LED controllers to simulate Lightning effects and experience the fish are not at all startled by it. The conclusion you can take from this is, it wasn't the light but the sudden conductive or inductive electrical power surge from the ballasts, starters and tubes likely were the cause running back and forth through the aquarium water and moist air under the hood. After all, light is light, and it ain't the light thus it was something else startling the fish and electricity as a cause is the only thing that remains in this scenario

Anyway, long story short a permanent pH probe grounds the tank and runs an (unknown) voltage through the tank or else it can not measure anything. It also grounds the tank to make all other currents be it inductive or capacitive to run to the ground. In how far your fish will be affected and feel a constant sensation that shouldn't be there or not remains to be seen.

I only think you should know, have your thoughts and make your own decision about it. 

I decided I had my fair share of CO² experiences, I liked it, but rather keep going low tech for the rest of my aquarium carrier, less hassle. And i do not ground my aquariums, I pull the power plugs before I stick my fingers in it for my own safety.

Btw if you are curious, get a multimeter and set it to measure voltage put the positive pin in the tank water and ground the negative pin. In 9 out of 10 aquariums you will measure a voltage, there are people that reported up to 60-volts others much less. In most cases, this is capacitive voltage. But this is the voltage that will run as a current to the ground if it is grounded.


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## NotoriousENG (22 Nov 2021)

@zozo, Thank you for the detailed reply!

I do have a dual-stage regulator that I ran tanks all the way dry with before and have never had any issues with end of tank dump. So if I go the controller route, preventing the end of tank dump wouldn't be the main motivation but I always like some extra redundancies. If do end up with a controller it's more so that the cost difference between the monitor is marginal and gives me the chance to try some new tech out. Also, thank you for pointing out the possibility of current leak. That's not something that would have occurred to me. I'm curious now so I will have to dig out my multimeter and see what kind of voltage readings I get from a tank as it stands now.

So it seems the bigger question is if the monitor is worth it over a pen-style meter. If it's not, can anyone recommend a pH pen? I'm also currently looking at upgrading my lighting so need to weigh the benefits of where my money is best spent. I know for sure I want to get a pH meter before the lights to make sure my CO2 is dialed in, but any money I save on the meter I can put towards the light.


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## Zeus. (23 Nov 2021)

As @zozo points out my pH controller use to change pH reading when my T5's came on, it wasn't an issue for me as I was using my pH Controller for just the pH drop period at the time and PLC was taking care of timings after that. pH pens are great but its also handy to have the probe on a wire so you can check the pH at various depths of the tank. I do use my pH controller as a monitor nowadays and replacement BNC probes are widely available and pretty cheap, where as my Hanna pH pen is great also but new pH 'tip' is more x3 expensive then the BNC type.
Both have their pros and cons


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## zozo (23 Nov 2021)

NotoriousENG said:


> So it seems the bigger question is if the monitor is worth it over a pen-style meter.



It depends actually on your own perception of convenience.  For me personally, in the beginning, it was a nice gadget to have and play with, but after a while not noticing many changes this will become less of an eyecatcher and is just a gadget that is there for what it is. After all, pH isn't that significantly important by itself as long as it stays in acceptable ranges. A drop checker with the correct solution will finally give you a somewhat correct reading to, how accurate it is within an acceptable range is of minor importance as long as it is stable.

Because of some acquaintances in the professional agricultural trade, I have easy access to such equipment and had my hands on quite some different pH meters pockets and permanents from different brands. And I can tell even if all correctly calibrated no 2 gave the same reading and all were off from each other within a few points. Thus I actually never could find out which one was correct.  Bottom line all this measuring actually only got me more confused than I already was. In some cases, it was indeed other devices electrical interference throwing the reading off. Since it measured correctly (?) in a cup but not in the fish tank.

Regarding controllers a used Milwaukee for a while and as @Zeus describes this one was rather susceptible to interferences, the build-in relay and solenoid started to rattle like mad if another electrical device was to close. The darn thing jump around when my cell phone came close or when the heater came on. Finally, the solution was putting this probe in line and outside the aquarium away from other electrical devices. I have also played with a Hanna Grocheck, this was the most stable meter but it had a separate ground pin and used a significantly higher voltage to measure. Even I could feel the sensation in my fingers. I came to the conclusion controllers are not really made with the idea for aquarium use regarding the fish perspective. They are original devices designed and used for the agriculture or chemical industry. It's the idea of convenience without giving a deeper thought that they also moved into the aquarium hobby.

Anyway if you want something fairly accurate i guess you have to look for a higher quality meter that will not be particularly cheap. Budget models will give budget results with an even bigger question mark. And after a while you might come to the conclusion, it's fun but actually don't really need to know what you're measuring. At least not in these so-called exact numbers.


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## NotoriousENG (27 Nov 2021)

After a lot of internal back and forth I ordered the American marine pinpoint pH monitor and some extra 4.0 and 7.0 calibration packets. I decided to go with the monitor over the controller as I'm not very good at topping up my tank and monitoring kH. I also use a good dual-stage regulator so I am not really worried about preventing end of tank dump as I have ran my tank all the way down without ill effects in the past. Since I'm just wanting a reliable way to measure my pH drop from CO2 I think this should meet my needs.

Choosing between the pinpoint and Milwaukee was much harder. The pinpoint seems to have better reviews and has better accuracy and resolution. However, it also sounds like it needs calibration more often. I could not get a definitive answer but I believe this is due to the pinpoint probe being single junction. The Milwaukee has lower resolution and accuracy but seems to have better probes that are gel-filled and double junction.

So hopefully I don't regret going with the pinpoint. If I have problems with the probes drifting I believe I can replace it with another BNC probe of another brand (the Milwaukee perhaps)?

On a side note, I stumbled across an old thread from Tom Bar on barreport about fitting a dissolved oxygen membrane filled with 4 dKH reference solutions to the end of a pH monitor probe. The theory is that it gives a digital drop checker with a faster response time. Since a reference solution is used it also allows the pH/kH charts to be accurate. Probably not worth the effort, but seemed like an interesting idea.

On a second side note, I dug out my multimeter, probed my tank, and measured no voltage, even on the millivolt scale. The only electrical equipment currently in my tank is the return pump as I don't use a heater. However, my multi-meter is cheap and by no means high quality so the results are questionable.


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