Apex Salinity Probe Heater Interaction / Curiosity

[Morpheosz]

I've noticed that my salt reading jumps up and down by approx 1ppt regularly on my Apex. It dawned on me that my temperature does that as well, from the heater going on and off so I used the overlay feature for the first time in the Apex graphing interface and found this very tight connection between my heater and salinity reading. It seems that when my heater is on, the salinity reading drops, and vice versa. I am using a Finnex Titanium heater if that matters, since it is metal.

Curious if others experience this as well and if it's a concern - e.g. is there stray voltage in the tank that could be a problem?

 

[blaxsun]

Have you enabled the TC feature on your salinity probe? (under the advanced tab) That helps stabilize the salinity reading. When enabled you have to recalibrate. I use a value of 2.1.

 

[Morpheosz]

Have you enabled the TC feature on your salinity probe? (under the advanced tab) That helps stabilize the salinity reading. When enabled you have to recalibrate. I use a value of 2.1.

Hey thanks for pointing that out, I don't recall setting it, but it is set to 2.2%. Maybe this is simply temp shift, but I suspect maybe not because my heater is a compartment downstream in my sump from this probe and I imagine the change in temp would be more gradual and this seems very pronounced?

 

[BanjoBandito]

WE ARE TALKING ABOUT THIS ON MY THREAD!!!! lol. Great minds think alike.....

 

[BanjoBandito]

I was directed here -

(Almost) Everything You Need to Know About Apex Salinity Calibration and TC Factor

I was trying to calibrate my new salinity probe a few weeks ago, and ran into all sorts of problems. Calibrations that were way off the mark, big fluctuations in readings that couldn't possibly be correct (and were verifiably not), etc. After searching around the internet, it was clear that a...

www.reef2reef.com

 

[Morpheosz]

Perfect! Maybe I should have been better about searching first lol

 

[BanjoBandito]

Perfect! Maybe I should have been better about searching first lol

You have to hit me with a brick sometimes, and it's way easier to just post something and have a fellow reefer calmly guide you to the answers.

 

[Morpheosz]

I was directed here -

(Almost) Everything You Need to Know About Apex Salinity Calibration and TC Factor

I was trying to calibrate my new salinity probe a few weeks ago, and ran into all sorts of problems. Calibrations that were way off the mark, big fluctuations in readings that couldn't possibly be correct (and were verifiably not), etc. After searching around the internet, it was clear that a...

www.reef2reef.com

I do wonder if I'm experiencing a different phenomenon. Both because my TC is already set to 2.2% and because that post shows a positive correlation between temp and salinity and my readings are showing an immediate inverse relationship between temp and salinity. That's why I hypothesize that it has more to do with interference with respect to the conductivity vs temp change. It doesn't seem feasible that when my heater goes on, down stream from the salinity probe, mixes slightly warmer water into the 75 gallons of the DT, and then comes back down into the sump and meets the salinity probe, that it would have that pronounced and immediate of a reaction. The temp probe is right above the heaters so it reacts quickly to the heat coming on but the salinity is as far downstream as it gets.

 

[ZombieEngineer]

The temp probe is right above the heaters so it reacts quickly to the heat coming on but the salinity is as far downstream as it gets.

This is your problem. Try moving your temp probe either next to your cond probe, in your tank, or in your overflow (if you do overflow put it in a chamber with direct contact to your main tank.

The quick response of the temp probe to the localized heat of your heaters is why you are getting the inverse relationship. The temp compensation is compensating differently than the temperature reaching the salinity probe. You will also see more stable temp control in your tank.

 

[Morpheosz]

This is your problem. Try moving your temp probe either next to your cond probe, in your tank, or in your overflow (if you do overflow put it in a chamber with direct contact to your main tank.

The quick response of the temp probe to the localized heat of your heaters is why you are getting the inverse relationship. The temp compensation is compensating differently than the temperature reaching the salinity probe. You will also see more stable temp control in your tank.

Good theory, I’ll give it a try, thanks!

 

[Morpheosz]

This is your problem. Try moving your temp probe either next to your cond probe, in your tank, or in your overflow (if you do overflow put it in a chamber with direct contact to your main tank.

The quick response of the temp probe to the localized heat of your heaters is why you are getting the inverse relationship. The temp compensation is compensating differently than the temperature reaching the salinity probe. You will also see more stable temp control in your tank.

You win the prize! Holy cow, that just smoothed it right out. Bonus - my heater is going on and off a lot less too since I also moved the Inkbird sensors upstream of the heaters as well as the Apex probe. Now they are all reading the well mixed DT water. I had always assumed the flow was enough through that chamber to smooth out the temperature changes when the heater is on and off but I guess it is clearly not!

Thank you!

 

[Morpheosz]

The last 20% is post the change...