Apex Salinity probe - inaccurate measurements?

B

Blitzer

New member
I thought it might stabilize over time, so have waited to post about the problems I'm having with my salinity probe. I have included a screenshot of my fusion measurements.

Dates of interest:
- March 30th: Calibrated probes and added to new tank with saltwater already running for a day
- April 1st: Readings seemed off, so recalibrated. Readings seem to be more in line with what I expected, but still much higher than the readings on my refractometer
- April 3rd: Added liverock
- April 4th: Inexplicable dip and rise, no changes made to the system at all. These are now lower than what I'm getting on my refractometer

I'd really like to rely on the readings, but they seem to be all over the place and never match my refractometer which reads consistent.

Any ideas?

i6mXcoL.png
 
I don't have salinity/conductivity probes, I know they say to keep their cables away from other cables, electro interference, is it possible there might be stray voltages in the tank? Try turning other electrical things off and on to see if your readings change when you do, also try the probe cable held right out of the way of other cables see if that helps, remember I don't know much about them
 
Scarface8 said:
I don't have salinity/conductivity probes, I know they say to keep their cables away from other cables, electro interference, is it possible there might be stray voltages in the tank? Try turning other electrical things off and on to see if your readings change when you do, also try the probe cable held right out of the way of other cables see if that helps, remember I don't know much about them
Click to expand...

I do have it near the other probes, tonight I'll try separating and ensuring the wire isn't touching any of the others to see if that helps
 
Stray voltages can be a pump that's cord may have a split in it or not 100% sealed, I had a power board next to my sump, it eventually got a real fine sort of salt crust on it, if I put my fingers in the tank I could feel a slight tingle around my finger nails or any fine cuts, that power board eventually started tripping my homes safety switches, I think the electrical interferences in the cables comes from mainly ac currents but I'm far from an expert, I'll try and find a video I watched a while ago and I'll post the link below some where
 
I've been running the Apex conductivity probe on my main system for several years now. I've also setup several others and all work fine but there are a couple things I always do when calibrating them. First, you should leave the probe in the water for up to a week before calibrating in order to allow the probe to break in. 2nd, you should have the probe in a dark area of the sump or system that is free of microbubbles. Lastly, never run probe cables parallel to power cables. If this is being used with a classic Apex, it's best to have a temp probe connected to the PM2. If this is on an Apex 2016, the temp compensation will run from the existing temp probe. Lastly, when calibrating, make sure the calibration solution is the same temp as the tank water otherwise, the temp compensation will be off assuming the Apex probe is in the tank water and not the calibration solution. Also, when I calibrate, I sue the Apex display to calibrate or the Apex.local web interface (not fusion) and allow the probe several minutes to settle. I also rinse in RODI water before calibrating and make sure the probe is good and dry for the dry calibration part by shaking the probe off very well and blowing on the tip as hard as I can several times.
 
One other thing. Are you calibrating your refractometer with refractometer calibration solution or distilled water? Using water to calibrate with will result in less accurate calibration. It's also important to have both the calibration solution and refractometer at room temperature for the most accurate calibration.
 
I also have had similar issues. In the end it seemed the probe was INCREDIBLY sensitive to flow. It would indicate perfect when I put it in the cal solution. Them crazy off in sump.. I even tried moving it to fuge.. I finally figured out that if I brought up Apex local.. and moved probe around sump.. I found a spot that constantly indicated within .5-1.0 of both my refractometer and Pinpoint monitor .. hope that helps .. good luck


Sent from my iPhone using Tapatalk
 
Update: I have moved the salinity probe away from the other probes and the same for the wire. The readings almost instantly moved back to the expected reading matching what my refractometer is showing.
 
Scarface8 said:
Nice one!! Glad to help out
Click to expand...

Yeah, thanks! It's so strange, dipped again and noticed the wire had drifted slightly to touch another wire. Seems to be super sensitive. Moved it again, and book back to normal readings. Will use some wire clips to run it far away from any other wire tonight!
 
Blitzer said:
Yeah, thanks! It's so strange, dipped again and noticed the wire had drifted slightly to touch another wire. Seems to be super sensitive. Moved it again, and book back to normal readings. Will use some wire clips to run it far away from any other wire tonight!
Click to expand...

i am guessing there is some sort of interference outside the tank that is causing that. Could be power wires running parallel to probe wires, a nearby DC pump or even stray voltage. My probe cables in my system as well as a few other systems I have setup with Apex and conductivity all have the probe wires touching eachother and none exhibit any kind of large variances in Conductivity. While moving the probes may appear to solve the issue, you are only fixing a symptom and not the root cause.
 
Is it possible to have your probe and module it's plugged into both far away from everything? And run you aquabus cable back to something else? For example have all apex gear on the right side of your setup, and then have just your probe and module on the left? That would surely isolate it from everything else
 
You must log in or register to reply here.

Similar threads

R
some random questions
Replies
1
Views
242
SantaMonica
S
T
Issue with Sump and turnover
Replies
2
Views
733
twiddybr
T
B
Apex Pro Failure - Lack of Support from Apex
Replies
4
Views
872
griss
griss
A
Aquarium Temperature Control: How I Hacked My Air Conditioner to control my tanks temperatures
Replies
6
Views
2K
Naso180
N
K
Carbon Dosing causes STN/RTN?
Replies
13
Views
3K
Timfish
Timfish
Back
Top