pH Monitors.....

[smcnally]

I'm starting to really dislike pH monitors. I always had a tough time keeping my pinpoint monitor calibrated and thought it was because I got it with an old probe. So instead of getting a new probe, I bought an AC Jr and slowly the pH dropped on me. At first I thought it was my tank that was actually dropping in pH, but then when I moved it over to this new tank I noticed it was reading a pH level of 6.8. I picked up some calibration solution and calibrated it and it acted like it calibrated fine...stick it in my tank and my pH is reading 7.19 right now. I tested it with a standard pH test and it is pretty much perfect at 8.2. What gives? What exactly is the point of a pH monitor when the seem to be off so much? I have yet to have one on my system that reads close to true for any substantial amount of time. I'm waiting on an answer from Curt over at neptune to find out if it is an issue with my AC Jr or the probe. I'll give one more probe a chance if he says that is what it is but will lose my faith in pH probes totally if I run into the same issues.

 

[penguinsix]

How old is the probe? May just be gone or damaged.

 

[smcnally]

Just looked it up and I got it the first week of January. It shouldn't be going bad that quick.

 

[MikeG]

I have used a Milwaukee which was spot on for about 1.5 years with a new probe about every 6 months and now use an aquacontroller 2 that has been accurate so far. I have had it for about 3 months. I also have a pinpoint monitor but haven't used it since I have the AC2. Curious what others experiences are.

 

[smcnally]

Mike, are you using the standard grade or lab grade probes?

 

[chew*]

lab grade probe on ac jr here is spot on at 8.25 lights just went out.

 

[origreefer]

Most probes have a very short shelf life. Let's say your store or worse online store, gets a ph monitor w/probe in stock in OCT. It was made in Sept. You buy it in NOV. That means, with 6 months shelf life, it might have just 3 months left on life till it's readings are unreliable. Most low end probes are terrible. I buy my probes from omega.com, ... lab grade, higher quality and yes higher cost. Buy a cheap monitor but spend the $$$ on a good probe.

 

[smcnally]

What I find REALLY weird is that the probe is reading 7.19 in my tank, but when put in a 7.0 solution, it is reading 7.74. It just makes no sense to me.

 

[KyleinCT]

I had a lab grade neptune go bad in less than a month...was fine then went haywire...up to the 9's...then back to normal, then schizo again.

I always keep a skeptical eye to the probe...I am running an old probe on a Milwaukee in my 75 and a newer regular prob on my AC in the 210.

 

[MikeG]

Mike, are you using the standard grade or lab grade probes?

I use all standard grade probes although I still have a true accumet lab probe that I havn't tried yet.

 

[marco67]

What I find REALLY weird is that the probe is reading 7.19 in my tank, but when put in a 7.0 solution, it is reading 7.74. It just makes no sense to me.

I've found a few times when the reading "just don't make sense" like that it's from a cracked bulb on the probe, check it carefully it could be just a hairline too.

 

[MikeG]

I've found a few times when the reading "just don't make sense" like that it's from a cracked bulb on the probe, check it carefully it could be just a hairline too.

Could also be some build up on the bulb. I normally make a habbit of soaking the probe in vinigar to help clean it up before I recalibrate it.

 

[origreefer]

What ever happened to Broadley James electrodes, they made the best. Good for at least 1 yr.

 

[chew*]

Its a good idea and reccomended to take a clean new soft bristle toothbrush to clean deposits out around the bulb. I do this once a month.

Once the probe can no longer be calibrated although most of you know this its time to get a new one, namely if you stick it in 7.0 for 1 hour like i do calibrate, rinse in RO then 10.0 1 hour and calibrate, rinse in RO and back into 7.0 and let it settle for 1/2 hour, if it doesnt read 7.0 the probe is no good.

 

[KyleinCT]

one hour? I just wait a few minutes till it stops changing? What's the benefit with the error rate of the standard probes?

 

[chew*]

/\

I use lab grade.........Its what a $50 difference between lab grade and normal probe, The corals in my tank total well over $600, its really a no brainer......

 

[MichaelJ]

I got a Milwaukee off of Mike G and haven't calibrated it since I got it... It read 7.9 for the longest time till I added two part solution and now goes from 8.1 to 8.3 So I'm going to NOT mess with mine in hopes of it working perfect. (I might be dilusional though)

 

[bbjohngm]

i have a standard grade pH probe on my ACjr and i calibrate it ever so often, not too much i'd say......but like someone stated before...when i calibrate it, it's a nice long process....i also let it sit in the solution for at least an hour before i rinse and go to the next solution.....i think this has a lot to do with it when you calibrate...doesn't the temp affect the outcome? so if the calibration solution is a different temp. shouldn't you let the probe sit to acclimate to the temp of the solution? At least that's what my thoughts were and that's why i wait so long....isn't there an option too (i think i remember reading in the manual) about auto temp compensation? can't remember....mine always seems spot on, although i haven't checked or calibrated it in a while....thanks for reminding me! lol

 

[smcnally]

Well I've been emailing back and fourth with Curt at Neptune and there may not be anything wrong with my probe. He said that if the serial interface is plugged in full time it can end up having a ground loop that causes erroneous pH (and ORP for the other models) readings. I'll need to remove my serial interface and recalibrate it to see if this is the issue I'm experiencing. If so, then I need to get a ground loop isolator to put on the cable.

 

[smcnally]

That is my problem. I unplugged the cable, reset the AC Jr, and it read 8.10. Plugged it back in and it dropped to 7.05. Damn...now I have to buy another part.