Digital Aquatics Salinity Probe Issue

[crs751]

I have an SL2V2 on my Archon system. At least twice, the most recent time just this weekend, the salinity in my tank dropped significantly causing coral to bleach. The controller didn't register this drop and I only found out what the actual salinity reading was by using my refractometer.

My lack of husbandry skills is not in question here; I should be more vigilant in checking the salinity, as well as other parameters, of my tank without relying solely on the controller. However, I thought I could at least rely somewhat on the controller to give me a warning.

Since the SL2V2 and probe were purchased used, is it possible the probe is defective and needs replaced? Typically how long do they last? I can calibrate it when necessary and it reads the same as the refractometer; I just can't trust it to monitor my salinity long term. What maintenance and how often do you perform to keep this probe viable?

Thanks for the input.

 

[pickupman66]

So my biggest beef with the salinity probe is the fact that when just emerged in your sump it is not accurate. There's too much chance for it to get little bubbles. Mine was constantly drifting down without getting out of calibration. What I ended up doing was putting it in line to a reactor feed by using a SharkBite fitting. It fit perfectly. Since doing this my probe has been Rock Steady and if I turn the reactor off and the tube goes dry it shows up with error. I will try and get a picture posted for you

 

[pickupman66]

Photo

 

[crs751]

Thanks Lindsey. So you don't think the probe is defective or needs replaced? I do have it in the display hanging downward, not certain why it locks up. Even with adding salt to raise my salinity it still shows the same reading as prior to the crash. Also, What size John Guest fitting do you use?

 

[pickupman66]

CRS. To check that it is working, pull the probe and perform a calibration on it. Use air as the zero and you can make your own 35ppt solution. Use 1 tbsp of salt per 182 ML of Ro/Di water.

run the calibration on it to see if it reads properly in both the zero and in the test solution. you should see a major difference in the two. If you dont, then the probe may be defective or it may need a good cleaning. you may wan to try and soak it in vinegar for a few hours to make sure no calcium deposits are on it.

 

[pickupman66]

Here is the last month or so of my graph. I shortened it because just before this was a water change when I shut everything down. the fluctuations are because the probe system and temperature probe are down sump from my heater. Heater is controlled by a temp probe inside the overflow.

 

[crs751]

Thanks, I'll clean it and calibrate looking for the warning signs you state in your post for a bad probe.

 

[n2585722]

When you calibrate it keep track of the raw data at o ppt and at 35 ppt. Like Lindsey said there sould be quite a difference between the 2 raw data reading. Also try placing the probe in some DI water to see what it reads. The reading should be quit low in DI water. The John Guest fitting would be 1/2". I got one at Lowes. Mine is like Lindsey's. It is inline with a reactor. What caused the salinity to drift that far out? Was there a leak?

 

[crs751]

Not certain but I believe my skimmer was set too wet and filled several times causing my top off to add fresh water. I have a drain on the skimmer cup and this could have caused me to loose track of how much fresh water was being added. I definitely need to be more vigilant.

 

[n2585722]

You may want to add a collection container to the drain of the skimmer with a float switch in it. Use the float switch with an alarm to turn off the skimmer if the container is full. I used a empty sandwich spread jar as a container. I have a extra so I can just swap them out and then empty and clean the full one. It is not unsusal to have this happen with a skimmer. Without some way to shut it down it could empty your sump. Use salinity alarms as a backup to this if yo want.

 

[crs751]

Yes I'll have to modify my setup for sure. I have a float to add to the collection cup but never got time to install it. I need to make time now.

 

[elmexotics]

We recommend replacing the probes every 12 -18 months, depending on the calcium levels of your tank. Higher calcium levels will cause a build up on the sensors of the salinity probe. This will interfere with the low powered magnetic field produced by the 2 polls in the sensor. The way Lindsey has it set up help prevent this from happening as it keeps the probe from sitting in standing water where the probe can easily get the build up.
When recalibrating, watch the raw data number, if they have a small spread, it is time to replace the probe.

 

[crs751]

Thanks for the advise Eric. This was a costly lesson learned for me as my SPS continue to bleach out even after I corrected the salinity. It appears Alk spiked so I'm certain if the salinity adjustment caused the spike but either way it is very frustrating. Will have to stabilize the tank and then decide how to proceed from there.

 

[pickupman66]

I hate to say this but sometimes the convenience items we have for our tanks can cause more harm than good. For instance an automatic top off that can input more water than our system can handle. Having a skimmer that could drain the tank of multiple gallons of water and then the top off flushing it back in. Unfortunately the technology that you had to hopefully detect this did not do the job correctly. However there are many that don't even have this.

 

[crs751]

You're right, in that the technology makes you complacent. At least it did for me. You have to be vigilant

 

[pickupman66]

So where you able to calibrate the probe?

 

[crs751]

I didn't try it yet. If I have time I'll try to do it tonight.

 

[crs751]

Today I finally had time to calibrate my probes. I started by trying to calibrate the pH probe on the port on the SL2V2. After 2-tries I was unable to do this. The first time it locked in on 7 and the second time it revised the raw data from the 7 calibration onto the 10 calibration line while I was calibrating the 7 solution. I moved this probe to one of the pH probes on the Archon and it calibrated flawlessly.

I calibrated the salinity probe next and the results were off from what i saw on a calibrated refractometer. And the spread for the calibration data was -1981 for air and -1172 for the 35ppt calibration solution.

Is there a problem with the module since I have problems calibrating its pH port or is the probe bad? Let me know what you think.

 

[n2585722]

I don't know what the issue was on the pH port. Do you have a way to hook the module to a computer with a SID to see if it has the current firmware? If you can update the firmware if it is not current. You can use PortCalibrate() command with the pH port once you get the raw data readings at 7 and 10. To use port calibrate you will need to know your module number and the port number of the port you are calibrating. To find that pick a unused output and select the controller function then show. Select the input. There are numbers at the left of the different imputs like "3:4" The first number is the module number and the second is the port. I think most of the modules with pH ports it will be port 4 with the exception of the Archon and the second port on the SLX. A port calibrate command is PortCalibrate(Modlue Number port Number,Low Calibrate Point, Low Calibrate Raw Data,High Calibrate Point,High Calibrate Raw Data).

Example: PortCalibrate(3:4,7.00,1050,10.00,-799)

This goes into the command line on the system page. It can also be used to do a two point temprature calibration on the temp ports. It has been awhile since I used this so I am going from memory. Lindsey or Eric if this is wrong then please correct me.

Your salinity raw data is not that far from mine. I did find out if you do a clean on it it is best to wait for several hours before calibrating it. I calibrated mine right after cleaning and it climbed to a reading of 47 before settling. It took about 24hrs.

 

[crs751]

Thanks for the reply. I'll check the module but I think it has the latest firmware. BTW how do you calibrate a temp probe. What temp value do you use?