Can’t get my PH probe to read correctly while in tank. Any tips?

AlexR · 03/16/2019, 08:49 PM

Anyone have any tips to get a PH probe to read correctly?

I have the probe on a reef angel controller. I have calibrated numerous times using the 7 and 10 solutions.

The probe will not go above 7.5ph while in the refugium. If I put the probe in a glass with tank water, but out of the tank it reads correctly 8.1 to 8.3ph.

I have put in grounding probes in my refugium and DT just to be sure there is no stray voltage.

On top of this I have a salinity probe close to the PH probe and the salinity probe reads correctly while in the refugium.

I placed the PH probe in the same chamber as the return pump, this is the least turbulent chamber in my refugium and had no micro bubbles.

This is really driving me nuts...

Are there any tips anyone knows of?

loudell · 03/16/2019, 08:53 PM

This may be shocking to you but have you considered that it could actually be your pH?

You can put the probe into 2 different (fresh pouches) of calibration fluid to see if it reads them correctly and you can conclude if the calibration fluid is read correctly then your refugium reading is also correct...

AlexR · 03/16/2019, 08:55 PM

Quote:

Originally Posted by loudell

This may be shocking to you but have you considered that it could actually be your pH?

You can put the probe into 2 different (fresh pouches) of calibration fluid to see if it reads them correctly and you can conclude if the calibration fluid is read correctly then your refugium reading is also correct...

In my original post I said I tested the same water in a glass and it read above 8.0.
I have also ran multiple test kits and all cane above 8.0.
So no - it’s not the correct readings.

Sent from my iPhone using Tapatalk

loudell · 03/16/2019, 08:59 PM

As you move that water sample from a (potentially sealed) refugium to a glass there is a good chance you are aerating it and degassing the CO2 which could be suppressing the reading to the low measurement you are seeing.
It is always best to measure pH in the tanke and not moving it to a glass or vial especially if it is going to be agitated or shaken prior to measurement.

AlexR · 03/16/2019, 08:59 PM

It’s funny. I’m asking for some help if advice and I get someone trying to make me out to be stupid...

It may come to a shock to you that I test my PH in more then one way.

Somehow the probe reads incorrectly only when in my refugium.
I did try to explain everything in my original post.

I would really appreciate advice from anyone with experience with PH probes.

Thanks.

AlexR · 03/16/2019, 09:01 PM

Quote:

Originally Posted by loudell

As you move that water sample from a (potentially sealed) refugium to a glass there is a good chance you are aerating it and degassing the CO2 which could be suppressing the reading to the low measurement you are seeing.

It is always best to measure pH in the tanke and not moving it to a glass or vial especially if it is going to be agitated or shaken prior to measurement.

I test PH using the high range API test kit.
It reads closer to 8.3 based on the test kit.

I’m sure my PH is not that low.

loudell · 03/16/2019, 09:03 PM

Please don't misunderstand me. I never intended to make any disparaging remarks. I just wanted to allow for the possibility of thinking outside the box to a possibility that the probe could potentially be correct.

I do have a pretty good understanding of pH instrumentation and just wanted to be helpful.

AlexR · 03/16/2019, 09:04 PM

Quote:

Originally Posted by loudell

Please don't misunderstand me. I never intended to make any disparaging remarks. I just wanted to allow for the possibility of thinking outside the box to a possibility that the probe could potentially be correct.

I do have a pretty good understanding of pH instrumentation and just wanted to be helpful.

I’m sorry. It’s easy to take things out of context. I’m just so frustrated with this thing.

loudell · 03/16/2019, 09:06 PM

pH is always best measured with a pH instrument referenced to high quality calibration fluids.

when you use the API Kit do you take the water sample out of the tank and shake it after the reagent is added? If so the sample is being actively degassed of CO2.

AlexR · 03/16/2019, 09:07 PM

Tomorrow I’m going to try and recalibrate it again.
It’s also a brand new probe.

Just to be sure I leave the doors open for the refugium all the time to air out and also leave the window open not far from the tank. No change on the probe reading.

AlexR · 03/16/2019, 09:09 PM

Quote:

Originally Posted by loudell

pH is always best measured with a pH instrument referenced to high quality calibration fluids.

when you use the API Kit do you take the water sample out of the tank and shake it after the reagent is added? If so the sample is being actively degassed of CO2.

I believe that’s how I do it. Is there another way?

AlexR · 03/16/2019, 09:18 PM

I’m also going to order another calibration fluid brand.
I’ve read some reviews saying the 7 calibration fluid was off.

loudell · 03/16/2019, 09:24 PM

IMO pH can not be accurately measured by taking the sample out of the tank and putting it into a vial with an airspace between the sample meniscus and vial cap only to be shaken. This will degass CO2 which has a strong impact on pH.
Obtain a good pH instrument with 2 point calibration a lab grade replaceable probe. Calibrate it and put into your system. If you see a suspicious reading just put the probe back into 2 different calibration fluids to see if it is indeed reading correctly or needs to be tweaked. Your pH instrument does not know how to read the calibration fluid correctly and be incorrect when it is in the refugium.

AlexR · 03/17/2019, 08:07 AM

Quote:

Originally Posted by loudell

IMO pH can not be accurately measured by taking the sample out of the tank and putting it into a vial with an airspace between the sample meniscus and vial cap only to be shaken. This will degass CO2 which has a strong impact on pH.
Obtain a good pH instrument with 2 point calibration a lab grade replaceable probe. Calibrate it and put into your system. If you see a suspicious reading just put the probe back into 2 different calibration fluids to see if it is indeed reading correctly or needs to be tweaked. Your pH instrument does not know how to read the calibration fluid correctly and be incorrect when it is in the refugium.

Are there not other factors?
Stray voltage? Micro bubbles? Vibration? Temperatures? Maybe others I don’t know about?

loudell · 03/17/2019, 09:36 AM

The factors of Stray voltage, temperature differences, micro bubbles, vibration are quoted frequently but the chances of them accounting for a low reading are just about zero.
Micro bubbles are a remote possibility however they can be easily diagnosed. If you suspect micro bubbles just swirl the tip of the probe to remove them and note the reading. If it stays the same there were no micro bubbles.
I have seen on rare occasion AC line voltage to the pH meter device exhibit interference but it is always a constantly unchanging reading and not a steady 0.4 off.

loudell · 03/17/2019, 09:37 AM

Can you take a picture of your refugium or describe its contents and the location of the pH probe?

AlexR · 03/17/2019, 09:38 AM

Quote:

Originally Posted by loudell

The factors of Stray voltage, temperature differences, micro bubbles, vibration are quoted frequently but the chances of them accounting for a low reading are just about zero.
Micro bubbles are a remote possibility however they can be easily diagnosed. If you suspect micro bubbles just swirl the tip of the probe to remove them and note the reading. If it stays the same there were no micro bubbles.
I have seen on rare occasion AC line voltage to the pH meter device exhibit interference but it is always a constantly unchanging reading and not a steady 0.4 off.

Ok... let’s say my PH is indeed this low.
I’m open to it.

What should I do to raise it?
Kalkwasser?

wrott · 03/17/2019, 09:45 AM

Do you use a Ca reactor?
And you did move the probe to all areas of the tank and still 7.5?
Usually interference will cause the reading to bounce around.

AlexR · 03/17/2019, 09:50 AM

Quote:

Originally Posted by wrott

Do you use a Ca reactor?
And you did move the probe to all areas of the tank and still 7.5?
Usually interference will cause the reading to bounce around.

I don’t use a Ca reactor.
I’ve tried everything except putting the probe in the DT.

loudell · 03/17/2019, 10:10 AM

Is the refugium loaded with calerpa, etc? and is the probe close to the algae?

AlexR · 03/17/2019, 11:01 AM

Quote:

Originally Posted by loudell

Is the refugium loaded with calerpa, etc? and is the probe close to the algae?

It is loaded with calerpa.
The probe is in another chamber about 5” away.

It’s a problem getting the probe in the DT to even test because the wire is not long enough.

AlexR · 03/17/2019, 11:04 AM

Quote:

Originally Posted by AlexR

It is loaded with calerpa.
The probe is in another chamber about 5” away.

It’s a problem getting the probe in the DT to even test because the wire is not long enough.

The refugium has about 5lbs of LR as well. It’s all in the center chamber with the algae.
The ph probe is in the right chamber with the main return pump, a couple small reactor pumps and the salinity probe.

As stated earlier I did put in grounding probe to eliminate any chance of stray voltage.
My main return pump is DC. I’m not sure about the reactor pumps. They are probably AC.
All my wave pumps in the DT are DC.

loudell · 03/17/2019, 11:08 AM

The calerpa is producing CO2 at times like all plants do. The fact that your refugium is loaded with calerpa and I bet it is very healthy means that you are probably producing a ton of CO2 which is depressing the pH to 7.5.
As an analogy think of the calerpa as a camp fire which produces heat. The closer you get the hotter it is. Your pH probe is very close to the camp fire. The fact that the windows are open does not really have enough impact to diffuse the CO2.
Get a pH probe with a longer cable or get an extension. Try measuring the pH in the tank perhaps at the point where the water enters the refugium. This may be your highest pH point.

loudell · 03/17/2019, 11:14 AM

I am not a fan of adding Kalkwasser or any chemical to counteract a phenomena that is normal and perhaps controllable.
Consider a better degassing plan for your outflow from the refugium and do not cover your tank which will trap an airspace layer of CO2 above your water line.
Definitely find a way or get another device to measure tank pH which should be different than the refugium campfire.

AlexR · 03/17/2019, 12:12 PM

Quote:

Originally Posted by loudell

I am not a fan of adding Kalkwasser or any chemical to counteract a phenomena that is normal and perhaps controllable.
Consider a better degassing plan for your outflow from the refugium and do not cover your tank which will trap an airspace layer of CO2 above your water line.
Definitely find a way or get another device to measure tank pH which should be different than the refugium campfire.

My tank is mostly open. It is covered a bit on the sides for safety. The entire middle is open.
I’ll see if I can get a extension for the probe and place it in the DT and see if it reads differently.

03/16/2019, 08:49 PM	#1
AlexR Premium Member Join Date: Oct 2000 Location: Palm Coast, FL Posts: 574	Can’t get my PH probe to read correctly while in tank. Any tips? Anyone have any tips to get a PH probe to read correctly? I have the probe on a reef angel controller. I have calibrated numerous times using the 7 and 10 solutions. The probe will not go above 7.5ph while in the refugium. If I put the probe in a glass with tank water, but out of the tank it reads correctly 8.1 to 8.3ph. I have put in grounding probes in my refugium and DT just to be sure there is no stray voltage. On top of this I have a salinity probe close to the PH probe and the salinity probe reads correctly while in the refugium. I placed the PH probe in the same chamber as the return pump, this is the least turbulent chamber in my refugium and had no micro bubbles. This is really driving me nuts... Are there any tips anyone knows of?

03/17/2019, 09:45 AM	#18
wrott Registered Member Join Date: Mar 2004 Location: Alabama Posts: 2,912	Do you use a Ca reactor? And you did move the probe to all areas of the tank and still 7.5? Usually interference will cause the reading to bounce around. __________________ OK, but where does the meat go! ------------------------------------------------ 120g SPS, 125g mix, 56g FOWLR, 20g qt

03/16/2019, 08:53 PM	#2
loudell Registered Member Join Date: May 2003 Posts: 367	This may be shocking to you but have you considered that it could actually be your pH? You can put the probe into 2 different (fresh pouches) of calibration fluid to see if it reads them correctly and you can conclude if the calibration fluid is read correctly then your refugium reading is also correct...

03/16/2019, 08:59 PM	#4
loudell Registered Member Join Date: May 2003 Posts: 367	As you move that water sample from a (potentially sealed) refugium to a glass there is a good chance you are aerating it and degassing the CO2 which could be suppressing the reading to the low measurement you are seeing. It is always best to measure pH in the tanke and not moving it to a glass or vial especially if it is going to be agitated or shaken prior to measurement.

03/16/2019, 09:03 PM	#7
loudell Registered Member Join Date: May 2003 Posts: 367	Please don't misunderstand me. I never intended to make any disparaging remarks. I just wanted to allow for the possibility of thinking outside the box to a possibility that the probe could potentially be correct. I do have a pretty good understanding of pH instrumentation and just wanted to be helpful.

03/16/2019, 09:06 PM	#9
loudell Registered Member Join Date: May 2003 Posts: 367	pH is always best measured with a pH instrument referenced to high quality calibration fluids. when you use the API Kit do you take the water sample out of the tank and shake it after the reagent is added? If so the sample is being actively degassed of CO2.

03/16/2019, 09:07 PM	#10
AlexR Premium Member Join Date: Oct 2000 Location: Palm Coast, FL Posts: 574	Tomorrow I’m going to try and recalibrate it again. It’s also a brand new probe. Just to be sure I leave the doors open for the refugium all the time to air out and also leave the window open not far from the tank. No change on the probe reading.

03/16/2019, 09:18 PM	#12
AlexR Premium Member Join Date: Oct 2000 Location: Palm Coast, FL Posts: 574	I’m also going to order another calibration fluid brand. I’ve read some reviews saying the 7 calibration fluid was off.

03/16/2019, 09:24 PM	#13
loudell Registered Member Join Date: May 2003 Posts: 367	IMO pH can not be accurately measured by taking the sample out of the tank and putting it into a vial with an airspace between the sample meniscus and vial cap only to be shaken. This will degass CO2 which has a strong impact on pH. Obtain a good pH instrument with 2 point calibration a lab grade replaceable probe. Calibrate it and put into your system. If you see a suspicious reading just put the probe back into 2 different calibration fluids to see if it is indeed reading correctly or needs to be tweaked. Your pH instrument does not know how to read the calibration fluid correctly and be incorrect when it is in the refugium.

03/17/2019, 09:36 AM	#15
loudell Registered Member Join Date: May 2003 Posts: 367	The factors of Stray voltage, temperature differences, micro bubbles, vibration are quoted frequently but the chances of them accounting for a low reading are just about zero. Micro bubbles are a remote possibility however they can be easily diagnosed. If you suspect micro bubbles just swirl the tip of the probe to remove them and note the reading. If it stays the same there were no micro bubbles. I have seen on rare occasion AC line voltage to the pH meter device exhibit interference but it is always a constantly unchanging reading and not a steady 0.4 off.

03/17/2019, 09:37 AM	#16
loudell Registered Member Join Date: May 2003 Posts: 367	Can you take a picture of your refugium or describe its contents and the location of the pH probe?

03/17/2019, 10:10 AM	#20
loudell Registered Member Join Date: May 2003 Posts: 367	Is the refugium loaded with calerpa, etc? and is the probe close to the algae?

03/17/2019, 11:08 AM	#23
loudell Registered Member Join Date: May 2003 Posts: 367	The calerpa is producing CO2 at times like all plants do. The fact that your refugium is loaded with calerpa and I bet it is very healthy means that you are probably producing a ton of CO2 which is depressing the pH to 7.5. As an analogy think of the calerpa as a camp fire which produces heat. The closer you get the hotter it is. Your pH probe is very close to the camp fire. The fact that the windows are open does not really have enough impact to diffuse the CO2. Get a pH probe with a longer cable or get an extension. Try measuring the pH in the tank perhaps at the point where the water enters the refugium. This may be your highest pH point.

03/17/2019, 11:14 AM	#24
loudell Registered Member Join Date: May 2003 Posts: 367	I am not a fan of adding Kalkwasser or any chemical to counteract a phenomena that is normal and perhaps controllable. Consider a better degassing plan for your outflow from the refugium and do not cover your tank which will trap an airspace layer of CO2 above your water line. Definitely find a way or get another device to measure tank pH which should be different than the refugium campfire.