Do you trust the salinity measurement?

[DecadentCommand]

Hi All,

I just got a new APEX. I've been using a hydrometer for months and have learned to trust the 1.024-1.026 recommended range of the hydrometer.

My problem is my APEX says the salinity is 38.8 ppt. Which after using a conversion chart says the specific gravity is 1.029. But when I measure I'm getting 1.025 via the hydrometer.

My question is, what do I trust? The electronic prob I just calibrated? Or the low tech Hydrometer? My coral seems to be struggling, is it possible it's due to elevated salt levels?

-Doug

 

[Michael Naegeli]

I would never trust a hydrometer

 

[Hemmdog]

Check with a refractometer.

 

[Peace River]

Hi All,

I just got a new APEX. I've been using a hydrometer for months and have learned to trust the 1.024-1.026 recommended range of the hydrometer.

My problem is my APEX says the salinity is 38.8 ppt. Which after using a conversion chart says the specific gravity is 1.029. But when I measure I'm getting 1.025 via the hydrometer.

My question is, what do I trust? The electronic prob I just calibrated? Or the low tech Hydrometer? My coral seems to be struggling, is it possible it's due to elevated salt levels?

-Doug

You may want to get or make a calibration solution to check all testing options. I agree with @Hemmdog to check with a hydrometer if you have one (or can borrow one until you get one).

 

[DecadentCommand]

Well the APEX calibration solution provide with the APEX seemed to work fine. That leads me to believe that I should trust the APEX. But I also kind of want to believe the simplest piece of equipment.

But, I guess I'll go buy a refractometer tomorrow. I'll see if i should trust the single cheapest piece of equipment I bought with the aquarium.

 

[redfishbluefish]

When you say hydrometer, are you talking about a swing arm:

Or one that is a long glass tube?

The swing arm hydrometers are repeatedly inaccurate, while the glass hydrometers have the requirement of meeting the temperatures mentioned on the hydrometer.

Best bet, as mentioned, is a refractometer.

 

[DecadentCommand]

I've been using the swing arm version.

I'm going to make some calls and hopefully my LFS will have a refractometer I can use. Pretty sure they test water, just not sure about salinity. I don't want to make a purchase for only ever using the equipment once.

 

[AZMSGT]

Um.... you should not trust that swing arm Hydrometer. They are junk

 

[mtfish]

The apex is a conductivity meter and can vary due to electric interference and needs to be calibrated. The swing hydrometer can be accurate but can vary due to bubbles or friction. A glass hydrometer is very accurate and needs no calibration. A refractometer can also be accurate but needs to be calibrated. If it were me, I would use the apex for trends only, and get a glass hydrometer or refractometer. If getting a refractometer, get a temperature compensating one.

 

[AdamNC]

Be mindful of where you run the salinity probe wire. It is easily interfered with from power cords. Make sure your running that wire a good 6-8 inches away from any power cord. When I first got mine I made the mistake and it constantly ran at about 40ppt. I rerouted it and it now reads between 33-34ppt.

 

[Tuffyyyyy]

The apex is a conductivity meter and can vary due to electric interference and needs to be calibrated. The swing hydrometer can be accurate but can vary due to bubbles or friction. A glass hydrometer is very accurate and needs no calibration. A refractometer can also be accurate but needs to be calibrated. If it were me, I would use the apex for trends only, and get a glass hydrometer or refractometer. If getting a refractometer, get a temperature compensating one.

I think this is a good take. From the responses on this thread you’d think swing arms were capable of murder. They’re not amazing but they’ll get the job done. OP just listen to mtfish

 

[jrill]

I would want to keep the refractometer in my reef toolbox to keeps tabs on the accuracy of the Apex probe.

 

[Waters]

I have found the Apex salinity probe to not be very accurate....just consistent....which can still be very helpful. As others stated, I would pick up a refractrometer and some calibration fluid and use that to get your initial number. Then from that you can "calibrate" your apex salinity probe.

 

[Jay Z]

I'd trust my hydrometer over my apex probe. I do slam my hydrometer 2-3 times after its full to knock off any micro bubbles. I had issues with my refractometer's before too. had 3, all 3 showed different no matter what I did. Best one I have is a cheap one off amazon, worst one is the red sea.

I ended up mixing a custom solution through trial and error to get my apex probe reading right. Think it was 48 that made it settle at 35. I use it for reference now, not law. It does hold pretty steady now, usually only out 1/2 a point, but has been consistent, but I still have trust issues. Sometimes it will drop like the ato is stuck on, but its just micro bubble, just shake it and it shoots right back up, but that could be placement in my tank too.

The most accurate I found for me was the Apera AI235 5052 saltwater salinity tester. Turn it on, test first tank, wait 20 seconds for it to settle, carry around the house and check everything thing else. Been rock solid.

I also use their ph testers too. No issues on those either.

 

[Jay Z]

I have found the Apex salinity probe to not be very accurate....just consistent....which can still be very helpful. As others stated, I would pick up a refractrometer and some calibration fluid and use that to get your initial number. Then from that you can "calibrate" your apex salinity probe.

Wish they would put the salinity offset back in on the new versions.

 

[ScottB]

I also find my APEX conductivity probe to be consistent, but not accurate. I have two Veegee refractometers that very rarely need to be calibrated and I trust them.

In the end, I calibrated my probe to my tank water which consistently read 1.026 on both refractometers.

 

[AdamNC]

Wish they would put the salinity offset back in on the new versions.

They have the temp calibration now.

 

[Jay Z]

They have the temp calibration now.

Yeah, I need it to go negative like the old days for my setup. I'm sure they will handle it one day.

We had a convo on this before I here. They use to have a offset like the temp probe one where you could dial it right in. Then they changed it with the new version.

 

[DecadentCommand]

Well if you guys want an update. I bought a refractometer. And it gave a reading of 1.025.

So it seems the Hydrometer and refractometer are giving the same readings. So I'm going to assume the Apex probe is not accurate.

Kind of disappointing I spent all this money on the Apex and it didn't give an accurate reading.

 

[rkpetersen]

Just calibrate it again, and keep microbubbles away from it. Do the manual calibration, never automatic.
My Apex salinity probes on two systems are always spot on.