Salinity constantly dropping

[BeejReef]

Automatic Top-off Kit. Proprietary Neptune/Apex nonsense

not bashing neptune, but that's where I'd take a hard look. The OP's system is spotless. Very hard to imagine a leak going undetected.

*** Thought*** ok, so during feedings when the return is off... does the sump level rise high enough for a reverse siphon from whatever the ATK is, or to any dosing lines?

 

[sfin52]

I agree with possible back syphon

 

[Glenng78]

Teat your ATO water salinity to make sure it’s not back-flowing into there from the tank

Good call !!!!!!

 

[sharpimage]

for salinity to drop that much, you would have to loose an awful lot of water. It must be the atk back siphoning. Any other hoses or dosing tubes in the tank?

 

[Glenng78]

No dosing yet / tank is new . My a few zoas

 

[mcdrichj]

Are the ATO and AWC interfering with each other? Also +1 to checking ATO salinity.

 

[Glenng78]

ATO reservoir is at 0 - but again it is a 36 gallon trash can. There is NO AWC system

 

[Peace River]

While you are continuing to look for the underlying solution, you may want to consider disconnecting your ATO for a few days and add water manually in order to remove a variable from the equation. Good luck!

 

[Glenng78]

This is exactly what I’ve done

 

[BeejReef]

Something is out of order. Just can't for the life of me figure what.

I doubt it's the issue, but what is your salt mixing routine? Sometimes when you test salinity immediately after mixing, it reads high. Water changes would then be lowering your salinity.

Are you sure there are no leaks? I understand you have leak detectors, but have you inspected the floor/ceiling below the tank?

Does the salinity bottom out at 28ppt, or would it keep falling if you let it?
If it bottoms out and stays there, then it has to be something to do with your total system water volume... be it a level sensor, return pump, overflow, ato float switch... something would have to be overfilling your system.

Do you have an old-fashioned fill to line on the side of your sump? I'd def do that and watch it like a hawk during power downs/ups until it stabilizes. Maybe your overflow lines take some time for the air to purge and the siphon to start. That could drop your sump level enough to kick on the ato.... until the whole system was overfull enough to prevent it.

 

[Glenng78]

Very interesting and insightful. I gotta see about that start / stop theory

 

[Greg P]

How many System Gallons do you have?
Some math will tell you how much fresh water you'd need to swap to drop from 34.5 to 28 in just days.
Let's get this math done. This way you can rule out physical water changes.
Then you can move on to hardware issues. Calibration solution, damaged refractometer etc.

For my 115g system I'd have to replace over 10 gallons of SW with straight RO to drop mine that much.

 

[Glenng78]

It’s a waterbox 190.5 display. I believe that is 140 gal total, so let’s call it 135 working volume. The sump is the trigger systems triton 44 which is 44 gal. I’ll take a pic of my working water level and you guys tell me what you think

 

[Justfebreezeit]

Initial thought is your atk is above your water level, im asumming you moved it there to shut the ato off for testing?

 

[Glenng78]

Yes exactly

 

[Glenng78]

I did notice my siphon break on the atk was in fact under water in my reservoir - so I tie wrapped it up. Although the outlet nozzle that sprays RO into the return chamber of the sump should pretty much be above the water level in the sump - but I may have overfilled the sump during my filling to raise salinity , causing a siphon back to the RO reservoir

 

[Glenng78]

The brute can next to the stand is the RO reservoir

 

[Glenng78]

I may have been siphoning during feed mode - which I have set to 15 min. Here is my water level in the sump during feed.

 

[Glenng78]

The atk is way high right now as I had removed it from the process to rule out the siphoning.

 

[Greg P]

So you've got 160-180g system total. To drop it from 1.025/6 to 1.023/4 in a couple days, you'd have to remove over 15g of SW and replace it with straight RO.
Have you gone through that much in your ATO in a couple days?