pH readings not stable

[P_tang]

Anyone have any ideas why my pH probe reading would be continuously unstable and constantly flickering between 7.9-8.1? This changes significantly when my skimmer is turned off, and will drop to 3-5 (which obviously isn’t accurate since my tank inhabitants are doing very well). It is the pinpoint monitor, and the probe is placed in the return section of the sump...

 

[frostyjay1]

Following since I have similar situations

things to try that I have
1. Open a window in the room
2. Run a tube from the skimmer inlet to a window

 

[Mical]

You said Ph is flickering, is it doing it within moments or over the course of hours? If it's doing it within minutes your cable to Ph probe is picking up electricity from a nearby cable. If it's over a period of hours and after turning off your skimmer, that's to be expected because your skimmer is aerating your water column when on. Your Ph swing between 7.9 - 8.1 is nothing to worry about.

 

[Kendrick Kemp]

IME. the probe is fine. ph fluctuate though out the day . peak at 2-5 pm starts to drop night early morning.
when skimmer is off less oxygen is being put in the water. less co2 is being forced out of tank.
but you can get higher ph. levels though other methods .. I guess my point is it not a probe problem.

 

[Crabs McJones]

How fast is the swing? If its throughout the day it's pretty normal. During the night (especially if you have a refugium) your ph will raise due to inactivity of household members. During the day when everyone is up and moving around and the fuge light or reactor is off ph will fall. Mine swings from 8.1-8.3 daily.

 

[dank reefer]

If it's an instant bump or decrease in reading s when turning on or off the skimmer, its electrical interference. I was having the same issue with a UV sterilizer and my Apex PH probe. Had to re run the wires in my stand for it to stop.

 

[P_tang]

I am not talking about the normal variation throughout the day....what I am trying to say is the reading is never a stable number. Within a second it reads 10 different numbers haha. And that continues throughout the day...continuously....

Sounds more like electrical interference I guess? Guess I don’t understand how that’s possible with the wires being insulated and all....

 

[Crabs McJones]

I am not talking about the normal variation throughout the day....what I am trying to say is the reading is never a stable number. Within a second it reads 10 different numbers haha. And that continues throughout the day...continuously....

Sounds more like electrical interference I guess? Guess I don’t understand how that’s possible with the wires being insulated and all....

Voltage leaking is a real thing. Those rubber insulators can and do fail. Best way to tell is to get a voltmeter (they can be picked up inexpensively from a hardware store) or if you know an electrician or mechanic that would let you borrow one for a couple of minutes to see.

 

[P_tang]

Voltage leaking is a real thing. Those rubber insulators can and do fail. Best way to tell is to get a voltmeter (they can be picked up inexpensively from a hardware store) or if you know an electrician or mechanic that would let you borrow one for a couple of minutes to see.

So you’re saying stray voltage in the water? If I were to get a voltage meter, I would just stick the probe in the water? And anything other than 0 is abnormal, I assume? Good thing I have a ground probe in there I guess huh?

 

[Crabs McJones]

So you’re saying stray voltage in the water? If I were to get a voltage meter, I would just stick the probe in the water? And anything other than 0 is abnormal, I assume? Good thing I have a ground probe in there I guess huh?

@Brew12 can explain it better than I would be able to. But my understanding is you put the negative probe in the ground of an outlet, and the positive in the tank water. You will get a reading no matter what as all equipment gives off traces of energy. But what you're looking for is spikes or unusually high voltage. For example, with all my equipment i've got about 12 volts running around my tank. I've recently gotten a titanium heater, and this removed it completely as they second as a ground probe.

 

[P_tang]

@Brew12 can explain it better than I would be able to. But my understanding is you put the negative probe in the ground of an outlet, and the positive in the tank water. You will get a reading no matter what as all equipment gives off traces of energy. But what you're looking for is spikes or unusually high voltage. For example, with all my equipment i've got about 12 volts running around my tank. I've recently gotten a titanium heater, and this removed it completely as they second as a ground probe.

Hmmm. Assuming that’s it, is there anything I can do about it? Or will I just never be able to determine my pH?

 

[Crabs McJones]

Hmmm. Assuming that’s it, is there anything I can do about it? Or will I just never be able to determine my pH?

If you do have high stray voltage, you have to identify what piece of equipment is causing it and replace or repair it.

 

[Brew12]

Thanks for the invite, @Crabs McJones !

Normally the probe issues are one of 3 causes. Induced voltages in a tank which can be fixed with a ground probe. Since you run one, this likely isn't it. Fault voltages can still cause problems even with a ground probe if they are low level. If you use a GFCI with a ground probe, this isn't a likely problem.

The third most common way this problem occurs is if your wiring on the pH probe runs right next to power cords for other equipment. Especially equipment with varying loads. You can try to run the pH probe wiring in the air by itself to see if this fixes it.

Another quick test to see if it is tank related or wiring related is to see how it responds in a small container of tank water. If it reads fine then you know it is something in the tank.

 

[Mical]

Thanks for the invite, @Crabs McJones !

The third most common way this problem occurs is if your wiring on the pH probe runs right next to power cords for other equipment. Especially equipment with varying loads. You can try to run the pH probe wiring in the air by itself to see if this fixes it.

Another quick test to see if it is tank related or wiring related is to see how it responds in a small container of tank water. If it reads fine then you know it is something in the tank.

+1 I'm betting his Ph probe cable is wrapped among other cables - mine was I first set up my tank and had same thing. The Apex graphs were insane.

 

[P_tang]

+1 I'm betting his Ph probe cable is wrapped among other cables - mine was I first set up my tank and had same thing. The Apex graphs were insane.

Oh it for sure is. I’ll do that test when I get the chance. Hopefully it’s just the interference as you described instead of a bunch of stray voltage.

 

[Randy Holmes-Farley Verified Community Expert]

I am not talking about the normal variation throughout the day....what I am trying to say is the reading is never a stable number. Within a second it reads 10 different numbers haha. And that continues throughout the day...continuously....

Sounds more like electrical interference I guess? Guess I don’t understand how that’s possible with the wires being insulated and all....

yes, it might be electrical interference. Insulation does not prevent through the air interference from lighting ballasts and other electrical sources.Try moving it away from other equipment, even try in a cup away from the tank.

 

[dank reefer]

Tedious but easy way to check is to disconnect 1 piece of equipment for 10 min or so and see if it's still erratic. Then you'll really know if its electrical or not.