Aragonite affecting pH probe

[rishma]

I am baffled.

I have a pH probe with my Apex. The probe is a Neptune lab grade, 3 months old.

I added live sand ( aragalive?) a couple weeks ago and noticed my pH was 0.2 lower on average in the following days. After a week I recalibrated the probe and found the pH back to normal, the probe had been out of calibration. That was 2 days ago.

Last night and moved some sand around. This created a little dust but did not badly cloud the water. The speed thing is my pH probe immediately flat lined and has not moved much in 11 hours, not filling my normal day/night trends.

Why would the dust from the sand mess up the probe calibration?

[rishma]

Not after a week...recalibrated after 2 weeks...

[orcafood]

The little glss bulb on the tip of the probe works by H+ hydrating the thin membranes SiOH bonds only at the outter surface. The resistance across the glass bulb changes based on number of hydrated SiOHH+ but as you would guess that signal is very very weak to begin with. Cloud the probe surface up with who knows what from the sand and it will change the resistance/pH drastically. The glass bulb on a pH probe must be kept immaculately clean.

[rishma]

I had no idea it was that sensitive. Have not had sand in many years.

Do others remove their probes when doing water changes, etc?

[orcafood]

I don’t own a probe but I have monitored many a reaction with one. They foul very easy!

The electronics that boost the signal are very similar to an electric guitar amp :) Less distortion please

[bertoni]

Water changes might cause a problem if there's a lot of debris stirred up, but I suspect that's unlikely. Adding sand is very likely to cause debris buildup, so I'm not that surprised about the problem. I would clean and calibrate the probe every month, and also I'd clean and calibrate it before taking any drastic action based on the measured pH level.

[kenneth wolfe]

The little glss bulb on the tip of the probe works by H+ hydrating the thin membranes SiOH bonds only at the outter surface. The resistance across the glass bulb changes based on number of hydrated SiOHH+ but as you would guess that signal is very very weak to begin with. Cloud the probe surface up with who knows what from the sand and it will change the resistance/pH drastically. The glass bulb on a pH probe must be kept immaculately clean.Bs..immaculately clean..ha..bs..you guys always over complicate things, let it learn, track trends not numbers. Don't let apex make you chase numbers , stability is key use apex to see trends, its a falty devise a hart , its a data logger ,simple , turn your resolution up then you can see variations in trends. It's a tool not a promise of accurate numbers, all sensors need maintenance to stAy close to spec, after owning one for a few years, then you understand..Just saying

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[orcafood]

I agree with you! pH probes are very innacurate/ not to be trusted without cleaning, they are just to see “trends”. I couldn’t have restated this thread better myself :3 thanks

The initial question was can my pH probe tip foul and get less accurate upon sand addition. What is your answer to that, yes or no?

[rishma]

Bs..immaculately clean..ha..bs..you guys always over complicate things, let it learn, track trends not numbers. Don't let apex make you chase numbers , stability is key use apex to see trends, its a falty devise a hart , its a data logger ,simple , turn your resolution up then you can see variations in trends. It's a tool not a promise of accurate numbers, all sensors need maintenance to stAy close to spec, after owning one for a few years, then you understand..Just saying

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Perhaps you didn't mean to be condescending. I'll give you the benefit of the doubt.

It's not the absolute number, but the fact that the probe is NOT trending as it should that raised my question.

Thanks all for info.

[kenneth wolfe]

Not trying to be smart was, my apologies..

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[ca1ore]

Trouble with any probe (maybe temp excepted) is that they are easily skewed by environmental crap (literally and figuratively). Dust, bubbles, electronic fields, etc. I experimented with different locations for mine (pH, Cond, ORP); ultimately concluding that the RDSB tank was the least 'disruptive'. You always want to be careful about what you control with probe readings.

[kenneth wolfe]

The probe , the double junction, imo only degraded in small , I mean small, increments, then it showed very unusual readings , clean in vinegar and it was close to original, recalibrated and ok, then it after that it was a a few more times then I replaced it, there good probes, I did have a New one that was bad, brs was replaced , my answer is no , I don't believe sediments effects ph probe that way, I can look at mine and see stuff on it, it's not newish looking it has algae on it. Just saying, calibration seems to be your problem.

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[kenneth wolfe]

What kind of ph probe are you using

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[orcafood]

http://www.getbluelab.com/site/bluelabassist/files/Product%20Manuals/Bluelab-pHProbe-Clean-DEC13.pdf

Be careful how you clean it :) The nicer the OP amp you have, the more you will notice a dirty probe. Probes themselves can be made dirt cheap, they are just a half cell with silver/ silver chloride. We could make one from an xmas bulb if we wanted haha :)

[orcafood]

http://hannainst.com/ph-electrode-maintenance-calibration-guide

[kenneth wolfe]

Thought about it some more , it wasn't the dust , it may have been from the gas released from the sand bed

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[rishma]

Thought about it some more , it wasn't the dust , it may have been from the gas released from the sand bed

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First occurred when brand new sand dumped in.

[kenneth wolfe]

Was the sand rinsed, might just be like dumping some kalk in the fine dust broke down.

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[rishma]

Not rinsed, live sand in bag. It was in there two weeks and when I stirred it up, more dust came up and pH probe went wacky again.

[n2585722]

You do know CO2 has a dramatic effect on pH. You probably had your CO2 content in the water rise after adding the sand. When I have all 5 grandkids at the house my pH drops dramatically until they leave. I can usually tell when they come and go during the day. That drives my wife crazy when I tell her when they went out and come back during the day. It also went up considerably when we were gone for a few days. One person staying home will lower the pH for that day a little.


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[dkeller_nc]

Keep in mind that there's always a possibility of "correlation without causation". pH probes will sometimes develop electrical connection problems in the cord, the electrode itself, or the BNC fitting. Moving the probe or otherwise messing with it can interrupt the connection between the meter and the probe, resulting in a "flat line" that doesn't respond to obvious changes in pH.

From the standpoint of the probe itself, I'd offer the following observations.
Replacing the probe is best - they're cheap. If you'd rather not replace the probe and want to try cleaning it, I'd recommend the following:

Remove the probe from the tank and rinse it. Contrary to the admonishment in the link Orca posted, rinsing with RODI will not damage the type of gel electrodes we use in our tank in any way, but tap water's OK as well. Prepare a solution of 0.1N hydrochloric acid - that's about a 1:100 dilution of concentrated hydrochloric acid sold for pool pH adjustment. Soak the bottom part of the probe in this acid solution for 30 minutes or so. Rinse thoroughly with tap or RODI, and recalibrate it with 7.0 and 10.0 pH buffer standards.

The reason for using 0.1N HCl in this case is that it is extremely effective at removing calcium carbonate deposits, and will also denature and remove any protein coating on the pH electrode's junction.

After performing the cleaning step, if the pH probe will not calibrate correctly, then it's trashed and must be replaced.

[kenneth wolfe]

I am baffled.

I have a pH probe with my Apex. The probe is a Neptune lab grade, 3 months old.

I added live sand ( aragalive?) a couple weeks ago and noticed my pH was 0.2 lower on average in the following days. After a week I recalibrated the probe and found the pH back to normal, the probe had been out of calibration. That was 2 days ago.

Last night and moved some sand around. This created a little dust but did not badly cloud the water. The speed thing is my pH probe immediately flat lined and has not moved much in 11 hours, not filling my normal day/night trends.

Why would the dust from the sand mess up the probe calibration?Just did some cleaning and remembered this thread, mine did the same, its from the cloudiness reducing photosynthesis, wathedit in apex , after it cleared it was back to rising, but never maid it to where it was the day before, next day it was normal again.

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