Salinity probe with DC pump

**Bigdog** · 01-13-2016

My salinity probe has been very stable for months and running between 34.5 and 34.7 depending on temp swings. I changed my return pump and installed a Red Dragon 80w DC return pump. When the new DC is running the salinity probe drops about 2 point. Turn off the pump and it returns to normal. I know the probes can be subject to interference so I tried rerouting the cable and this did not help. Moved it from the sump to the DT and it reports 45.5 to 46 with the pump running.

At this point I would like to return it to the sump since moving to the DT is even worse. The question is will re calibrating with the DC pump running allow it to report correctly? Anything else that can be done to address the issue?

Thanks in advance for the help.

**jrlamountain** · 01-14-2016

Did u check for stray voltage ?

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**Bigdog** · 01-15-2016

I had not checked for stray voltage but will. Out of town till this afternoon but will check then.

thanks

**Bigdog** · 01-16-2016

Just checked for stray voltage in the tank and sump and found nothing. I use pretty high end equipment so would have been surprised to find any stray voltage.

Any other ideas? Would re calibrating it based on the new pump running be advisable?

Thanks

**jrlamountain** · 01-16-2016

Must be some kind of interference then

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**iamchadster** · 01-16-2016

Originally Posted by Bigdog

Just checked for stray voltage in the tank and sump and found nothing. I use pretty high end equipment so would have been surprised to find any stray voltage.

Any other ideas? Would re calibrating it based on the new pump running be advisable?

Thanks

Checked for DC and AC?

**martyadamo** · 01-16-2016

I am trouble shooting the same thing right now with neptune support. My probe is all over and even more weird it drops two points at night when the heaters are on consistently. I have the salinity probe in a cup of tank water out of the sump for the last two days and it seems to be holding steady. I have the Vectra M1 DC pump and heaters in the same chamber and next chamber over. I have no idea what to do, everything is as cleanly wire managed as possible. I was thinking about adding a Ferrite Core to the probe cables but don't know if that will help. Let me know if you find something that works.

**Bigdog** · 01-17-2016

Originally Posted by iamchadster

Checked for DC and AC?

Hey Chad

How do you check it for DC? I checked it for AC only as the ground is common. Do you check it the same way for DC, meaning with the ground of the AC? The DC pump and controller are sealed to no way to get to the DC ground.

Thanks

**Bigdog** · 01-17-2016

Originally Posted by martyadamo

I am trouble shooting the same thing right now with neptune support. My probe is all over and even more weird it drops two points at night when the heaters are on consistently. I have the salinity probe in a cup of tank water out of the sump for the last two days and it seems to be holding steady. I have the Vectra M1 DC pump and heaters in the same chamber and next chamber over. I have no idea what to do, everything is as cleanly wire managed as possible. I was thinking about adding a Ferrite Core to the probe cables but don't know if that will help. Let me know if you find something that works.

Interesting for sure. I moved mine back to the sump and it has been very stable only fluctuating by .2-.3 based on temp swings but is off by about 4 points total. At this point I think I will try to re-calibrate it with teh DC pump running and see if it moved back to the 34.5 t 34.7 range. Has support suggested trying to re calibrate it?

thanks

**martyadamo** · 01-17-2016

Originally Posted by Bigdog

Interesting for sure. I moved mine back to the sump and it has been very stable only fluctuating by .2-.3 based on temp swings but is off by about 4 points total. At this point I think I will try to re-calibrate it with teh DC pump running and see if it moved back to the 34.5 t 34.7 range. Has support suggested trying to re calibrate it?

thanks

I've already re calibrated it twice once was with neptune controlling the re calibration through remote assistance. They saw while calibrating it that as soon as I moved the probe back to the sump the values changed. I also notice that when I shut the pump off during feed cycles the salinity sky rockets. My guess is when the pump shuts down the interference stops and thats why the value goes up. I'm waiting to contact them back on Tuesday or Wednesday to see what the options are. Maybe the ferrite cores, not sure.

**Adsjj** · 01-19-2016

Following this as I have 3 dc pumps in my sump and just got an apex, really wanted the salinity probe and module but if I'm going to get incorrect readings I may not bother. it sounds like its a form of electrical interference so could a ground probe work? however will a titanium probe then leach titanium into the water over time?

Martyadamo please do update this thread once you find out I'm sure a lot of us will be very interested what Apex suggest

**Bigdog** · 01-19-2016

Yeah it is definitely interference from the DC pumps. If I turn mine off the reading changed immediately. For what it is worth I do have a ground probe and there was no change in the reading with or without it.

**Adsjj** · 01-19-2016

I was hoping the probe would help as it is a rather cheap thing to put in place to get around an issue, thanks for letting us know a probe wont do anything, will be interesting what other things can be done to get around this issue, everyone seems to be going to DC pumps now for low running cost so you would think that many people have the same issue.

**martyadamo** · 01-20-2016

Originally Posted by Adsjj

I was hoping the probe would help as it is a rather cheap thing to put in place to get around an issue, thanks for letting us know a probe wont do anything, will be interesting what other things can be done to get around this issue, everyone seems to be going to DC pumps now for low running cost so you would think that many people have the same issue.

I am going to get a ferrite core today and see if that makes any difference. Neptune emailed me back and said it is definitely interference and I could try the ferrite core but didn't offer up any other ideas. I would think they need to make a change with the salinity probe so that it isn't as susceptible to interference. They are going to be selling a DC pump soon so you would think they would want all their equipment to work together. I guess we will see.

**Bigdog** · 01-20-2016

Ok great. Please report back your findings. I agree with the popularity of DC pumps something to eliminate the interference needs to be done.

**jrlamountain** · 01-20-2016

I use a dc return pump and a salinity probe with no issue it might be a bad pump

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**Adsjj** · 01-21-2016

do you have any issues with your PH fluctuating at all when you turn your pump on and off? or is it just the salinity probe?

**martyadamo** · 01-21-2016

Originally Posted by Adsjj

do you have any issues with your PH fluctuating at all when you turn your pump on and off? or is it just the salinity probe?

Its just the salinity probe, Neptune said themselves that the salinity probe is most susceptible to electrical magnetic interference. I tried the choke clamps or ferrite clamps and they did not help. I have a call into neptune to see if there is anything else that I can do. If I can't get it to work, I will be removing the PM2 module all together. I don't have a need for it, if its not going to operate properly.

**Adsjj** · 01-21-2016

Ye there's no point if it's not going to give you an accurate reading. I'm probably going to hold off paying out on that modual. I'd rather buy the vortech modual and the feeder which I can get them both for the price of the pm2 setup. A refractor will just have to be good enough for me at the moment until they update it and make a different probe

**Bigdog** · 01-21-2016

My PH probe and ORP probe are both stable and accurate with the DC pump running. It is just the salinity probe with issues.

**daquan44** · 01-21-2016

That's odd. I have the Vectra M1 and a salinity probe, and experience no issues. It may be due to the fact that the Vectra is in the sump, and the probe is in the main display.

**martyadamo** · 01-22-2016

Originally Posted by daquan44

That's odd. I have the Vectra M1 and a salinity probe, and experience no issues. It may be due to the fact that the Vectra is in the sump, and the probe is in the main display.

Yep, as soon as I move the probe out of the sump and into a cup of tank water the probe reads correct. Its only when the probe is in the sump in the next chamber over that it reads incorrect. How do you have it mounted in the DT? The only place I would be able to put it would be the overflow but the cord would show and I don't know if I would like that.

**Adsjj** · 01-22-2016

Is there any chance of getting the probe in the weir? It's strange that when the probe is in the dt it reads fine. Surely the current is still in the water column. The pump sending the water up the return pipe is still completing a circuit so I would have thought there would be some residual current in the water. Please correct me if I'm wrong that's just how I see it.

**daquan44** · 01-22-2016

I have my probe in the weir. The cord runs down the back of the display tank.

**fab** · 01-24-2016

You guys keep referring to this problem in terms of some kind of electrical interference. Does anyone know what the electrical nature of this interference is, yet?

Does anyone know anything about the susceptability modes of the conductivity probes? What forms and magnitudes of "interference" would cause bad readings?

Maybe Neptune could give us some details on this.
...PLEASE PLEASE PLEASE.
Have any of you that have this problem measured the voltage difference between various pairs of locations in your tanks? ...for instance between sump and electrical ground, between display tank and the same electrical ground location, and between the display tank and the sump? ...measuring AC voltage drop and DC voltage drop in each case. ... With each electrical device on and again with each one off, preferably one device at a time.

Resolving this issue will take a methodical and thorough course of diagnosis.

Another test would be to move a suspect electrical device ( a pump?) to a spare tank or even a bucket filled with system water from your sump|display tank and the conductivity probe and check the probe's behavior in isolation from your main system.
If it does not happen there, try wiggling the device's power cord and the probe's cable to see if you can cause the bad readings to show up.

Try a second conductivity probe.

These are examples of fault isolation steps you can take in trying to diagnose this problem.

Good luck and please post your results on the forum to benefit our entire community.