Salinity constantly dropping

[Greg P]

I was using a refractometer to confirm the apex reading

Read above about a faulty unit.
Put some thoroughly mixed salt in a container, test it and record the result, then seal the container.
Test it in a couple days. Did the test remain the same?
If not, your hardware is to blame

 

[Greg P]

I think my skimmer sucks up salt

All skimmers will remove some salt, but not 10-15g over a couple days. And if you're dosing any kind of 2-part it will make up for it.
I was dosing over 125mls/day on my last 75g and had to remove water to be replaced with RO every 2 weeks as the salts in the DIY would RAISE my Sg

 

[Greg P]

Does anyone know anything else that can suck up salinity?

Keep us updated Glenn

 

[Rubblereefer]

It’s definitely your refractometer and apex giving bad readings. I don’t have a salinity probe but from what I hear the apex is hit or miss with salinity and any micro bubbles or stray voltage can throw it way off. refractometers can break etc
If you were leaking enough water to drop your SG that much you’d know, and by now you would know if your top off was dumping that much extra ro water as well. Go Get one of those 15 dollar instant ocean swing arm hydrometers and check against that, this has to be your issue

 

[purp]

If you cal your apex salinity probe, make sure the temp probe is in the same unit as the conductivity probe or things will be way off!

 

[Glenng78]

Ok I disconnected the ATK for a day, and my salinity was stable at 34.1 on the apex and it was confirmed by the refractometer. So I thought I was good, I re connected the ATK to run like normal , and over the course of 1 day, my salinity dropped to 30.5. I put a siphon break at the very top of the hose that feeds the ATK inside the sump ( circled in yellow ). Also I made certain that during regular operation the water level in the sump is well below where a siphon could occur in that hose. During feed mode, the water level (illustrated in green) comes above the ATK output, but not anywhere near the siphon break. So at this point I am fairly certain it is not a reverse siphon back into the ATO reservoir. But the problem only occurs when the atk is running.

 

[Glenng78]

Also , the system did not go into feed mode at all during this time period.

 

[Glenng78]

BTW thank everyone for all their quick advice , that’s what makes this community great.

 

[Glenng78]

29.3 this morning

 

[Glenng78]

I want to believe the faulty test equipment theory, but why would the readings stabilize when my ATO is disconnected ?

 

[Glenng78]

28.9

 

[Glenng78]

Who has any good ideas? All of my probes are in the skimmer chamber. My sump is set up from left to right:
Refugium- skimmer and probes- return

 

[BeejReef]

I think you've found it. Something is wrong with the siphon break???
you were pretty methodical and deductive.
Just found this with a google search

Help! ATK PMUP siphon break doesn't break siphon

After getting my ATK setup with my Apex Jr. controller, I finally let the PMUP run. It worked great, and the PMUP stopped. I kept seeing a trickle of water come through though. At first I thought it was just emptying out some excess. But after 10 minutes, my second sensor was covered and I got...

forum.neptunesystems.com

 

[Glenng78]

Good find , but my siphon break works correctly , as I do get a stream of water spraying from it when the pump is active. Plus, that siphon break was only for redundancy, as the hose is never submerged unless I am in feed mode

 

[Glenng78]

Ok this is weird - I went all the way down to 27.1 today, I moved my whole probe rack into the refugium chamber instead of the skimmer chamber where it originally was- and I instantly went up to 34.7. what the heck

 

[Greg P]

I don't own an Apex so you have me stumped.
Must be a current issue.
My Reefkeeper won't correctly read my pH when plugged in to my PC for programming. This is a grounding issue I've read but can't solve and don't care about.

Regardless, glad you have started to figure out the issue.
Keep us posted for the sharing of knowledge !!

 

[Greg P]

Afterthought;
Do you own a multimeter? Can you do a stray current test in your skimmer chamber?

 

[Glenng78]

Interesting , but how would it ONLY be in my skimmer chamber ?

 

[Greg P]

Test with a meter.
Just hypothesizing here but could be the current in that chamber is messing with your controller.

Try putting the Apex probe in a cup of water and go from there.
Rule out things. Test, test, test

 

[Greg P]

Test the voltage in your skimmer chamber and then in your 'fuge.
Something must be upsetting your controller.
Again, I don't own an Apex

Do you use a ground probe in either chamber? Or at all?

Do you know how to test for stray voltage?