Salinity Testing Issue - Please Help!

[Fish Fan]

Now that you have your diy rhf salinity reference, you can feel safe 'calibrating' your milwaukee. Sounds like it is pretty close. Just wipe it off before and after each use.

Yes, it was easier to measure and make than I thought without a better scale, and I'm glad to know it keeps well, so I'll be using it more often.

 

[A_Blind_Reefer]

Maybe a few of us can do help with design and provide you ready to print files. I am sure somebody could also help you build some basic slicer presets if you need tweaks.

Next time something comes up I’ll be sure to ask for some help! I hate to ask as I’m a knothead but I appreciate it!

 

[MnFish1]

Hey guys!

I think this is the best section to ask this, RHF please move if appropriate :)

This is one of those very humbling things, I feel as though I’ve made a noob mistake (not that I think of myself as much more), and I’m not sure the best course of action, at least in the short term.

Backstory: I don’t have a typical refractometer currently, but about 18 months or so ago I bought a brand new Milwaukee digital refractometer, and I loved it. I calibrated it with distilled water and confirmed with prepared 35 ppt calibration fluid that came with the Milwaukee refractometer, and never gave it much more thought. It has been pointed out to me that it’s not the most accurate option we have, but the darn thing is so convenient, I loved using it, and I assumed it was good enough for what I was doing. At the time, I had two small tanks with some simple Zoas, shrooms, and gorgonians. I continued to occasionally recalibrate with distilled, but I neglected to confirm with a 35 ppt standard. And admittedly, I hadn’t recalibrated it at all in some time now.

More recently, I started a new 25 gallon, and wanted to try some stony corals. I ordered a small batch of frags from Tidal Gardens, delivered yesterday. I decided to test the water the frags came in, and with my Milwaukee they were in 38 ppt water. That seemed odd to me, I would think a place like Tidal Gardens would be right on with salinity, and certainly not high. So right there I started to doubt my Milwaukee. But in the interest of time, I started to slowly acclimate the corals to my tank water.

I also have a Hanna HI98319 Salinity Checker that I got used, if that’s important (perhaps it was incorrectly stored??). I calibrated the Hanna using Hanna’s 35 ppt packets (also came used, but sealed and not expired). I recalibrated the Milwaukee with distilled water. Now when I test my tank water, the Milwaukee reports 33 ppt and the Hanna reports 36.1 ppt. I’ve repeated both tests several times.

What’s really puzzling is that I poured a freshly opened Hanna 35 ppt packet on the Milwaukee, and the Milwaukee is reading that as 25 ppt. I did it three times, each time 25 ppt.

So what gives, and what do I do from here? Sadly, I believe I have frags dying in less than 24 hours, which may be due to other factors, but I have to believe this salinity testing confusion is the root of much of my troubles here :disappointed-face:

Would you be more likely to trust either of the two devices here more than the other?

Why do you think your salinity might be 'off'. I mean - if you've mixed your salt properly - it should be fine. It could be your refractometer is becoming defective - and you need a new one?

Yes, I know I need a standard, and yes I’m going to order the TM glass hydrometer and a 500 mL graduated cylinder (should have had one on hand long ago), but that won’t be here until next week, likely. I do like the option of an analog standard that does not need special storage or calibration, and I can use the graduated cylinder to make Randy’s DIY 35 ppt standard solution going forward.

I don't think a glass hydrometer should be the standard - I would use a standard visual refractometer.

I think my choices right now are:

• Trust one of my two salinity testers

You should get a third test - and calibrate both with 35 ppt, not distilled water

• Run 5 minutes to the pet store near me and grab a swing arm hydrometer

You could do that as a triple check

• Drive the 40 minutes or so each way to have a real LFS test the water

You could do that aslo

• EDIT: I have a PetCo near me that stocks the Imagitatrium refractometer

And, I feel like an idiot, I strongly believe that salinity is the number 1 parameter to stay on top of, and now this.

What would you guys do? Any help would be greatly appreciated! Thank you in advance!

If your salinity is 'off'' other things are going to be off as well. I would test all of the usual things (nitrate, PO4 Alk).

 

[ReefQuestCorals]

I see you have plenty of people to help here, but I have been using this refractometer for some time now without any issues. Calibrate it to 35ppt and it holds calibration without any issues. I have issues trusting technology and tend to stick to more traditional methods when it comes to this hobby :grinning-face-with-sweat:

 

[Fish Fan]

I see you have plenty of people to help here, but I have been using this refractometer for some time now without any issues. Calibrate it to 35ppt and it holds calibration without any issues. I have issues trusting technology and tend to stick to more traditional methods when it comes to this hobby :grinning-face-with-sweat:

Thank you for your help here! I've used those refractometers a lot over the years, and at this time I don't have one, and don't really want one now that I've confirmed that my Milwaukee is working well. I much prefer having a digital readout rather than squinting at anything, especially now that my eyes are not so great. But I appreciate your suggestions, thank you again for your reply and help!

 

[Fish Fan]

Why do you think your salinity might be 'off'. I mean - if you've mixed your salt properly - it should be fine. It could be your refractometer is becoming defective - and you need a new one?

Thank you for your help and reply here! I began to suspect my Milwaulkee reftractometer was out of calibration when I tested the water that new frags came in and that water was 38 ppt. I still can't explain that, I wrote to the seller, and they said they keep those frags at 1.025-1.026 SG. After testing with Randy's DIY 35 ppt stadard solution, I am now confident that the Milwaukee is pretty much right on.

I don't think a glass hydrometer should be the standard - I would use a standard visual refractometer.

I'm going to disagree here, at least for me personally. I don't want anything that needs calibration or special storage, I like that the glass hydrometer is analog, and all you do is float it. The Tropic Marin hydrometer specifically seems like the one to get. I had a glass hydrometer when I was a kid, so this just seems right to me. I should have had one all along.

You should get a third test - and calibrate both with 35 ppt, not distilled water

A third test is indeed a good idea.

The Milwaukee refractometer is designed to be calibrated with distilled water, and indeed there is no option to calibrate it with 35 ppt solution, that's why I used distilled water for that one :)

You could do that as a triple check

I think for now I know the Milwaukee is at least working as it should, so for now I'm going to skip the swing arm and wait for the glass hydrometer to come in. I had the swing arm style a couple times in the past, and I don't particularly care for that style. It seems anything from a gas bubble to a sticking arm can skew the reading, at least in my experience.

If your salinity is 'off'' other things are going to be off as well. I would test all of the usual things (nitrate, PO4 Alk).

Agreed 110%! That's why I flipped out over all these salinity questions lol! I think I'm back on track, and certainly I'm double checking all other parameters too :)

Thank you again for your help here!

 

[BeanAnimal]

I don't think a glass hydrometer should be the standard - I would use a standard visual refractometer.

A quality glass hydrometer is factory calibrated. You can verify it against another calibrated device if you want, but it won’t ever drift or change. Once it’s verified (if you even feel the need), it never needs to be checked again. That makes it a true physical standard.

Also, the hydrometer is not temperature-dependent in the problematic sense. A simple lookup table gives you accurate temperature compensation.

A visual refractometer must be calibrated against a standard, and despite what “automatic temperature correction” claims suggest, it’s not truly temperature-compensated. On top of that, its accuracy depends entirely on the precision of the calibration solution. Therefore, your total error is the device’s own margin, plus the human factor in calibration, plus any deviation in the fluid.

A refractometer is not a standard, it is a test instrument that must be calibrated against a standard.

 

[Randy Holmes-Farley]

A quality glass hydrometer is factory calibrated.

Any idea how they do that? Or even if they do that, as opposed to make every one by the same basic process? It's not like it is marked on the outside of the glass.

 

[BeanAnimal]

Any idea how they do that? Or even if they do that, as opposed to make every one by the same basic process? It's not like it is marked on the outside of the glass.

Forgive the unpolished response. Typing from iPhone.

Actually yes. It is one of those burning "I need to know things" so I went down that rabbit hole several years ago. Partly because I had two very old hydrometers of the same model and they had different scales and scale card positions! (neatly hand written, btw)

My understanding after spending far too much time doing research and reading.

In most modern instruments, the cards are not individualized, the scale is fixed. Cards are inserted to a pre-calculated position and the stem is flame sealed.

For high precision models or NIST traceable instruments, each device may be floated and verified to be within published specifications.

In some high end models the instrument would be floated and the card adjusted before the neck is sealed. But cards are still not typically custom.

Older instruments were hand blown. The instrument would be floated, possibly in 2 or 3 different standards, and a custom scale derived and printed and sealed into the neck in the proper position, as determined by floating it.

The Tropic Marin? I assume is blown into a mold, and the card shoved in to a fixed depth and the instrument is sealed. I imagine that batch or random testing is done to assure they meet the specified precision.

This works fairly well because the volume is fixed by the mold that the glass is blown into and there is enough ballast to override any minor differences in glass mass between individual instruments.

 

[Fish Fan]

@BeanAnimal Is the Tropic Marin hydrometer a good choice for hobbyists looking to verify other testing?

 

[BeanAnimal]

@BeanAnimal Is the Tropic Marin hydrometer a good choice for hobbyists looking to verify other testing?

In my opinion it is.

Two reasons:

1 - actual pinpoint (no pun) salinity is not important. I would not even argue that stability isn't either. But what is important is knowing that your instrument is reliably not drifting. In other words, if it reads error, it always reads the same amount of error.

2 - it is not overly expensive and because it does not drift, it can be used to keep devices that do drift calibrated.

It is not the only solution and it may not be the best solution. Randy's standard is another very easy way to produce a standard for other types of devices.

 

[Fish Fan]

In my opinion it is.

Two reasons:

1 - actual pinpoint (no pun) salinity is not important. I would not even argue that stability isn't either. But what is important is knowing that your instrument is reliably not drifting. In other words, if it reads error, it always reads the same amount of error.

2 - it is not overly expensive and because it does not drift, it can be used to keep devices that do drift calibrated.

It is not the only solution and it may not be the best solution. Randy's standard is another very easy way to produce a standard for other types of devices.

Thank you for your help!

 

[edsbeaker]

I just wanted to add that I have had a great experience with my TM hydrometer. It has been my main measuring for salinity for the last year. I have used digital and refractometers and because they need to be calibrated and do drift I was always self guessing about its accuracy. A few negatives are that the hydrometer is a bit more cumbersome to use, it’s big, and it’s fragile, and if using in your tank all the pumps need to be turned off. Also, as you know if the water temp isn’t at its 77 calibrated degrees, you do have to use a calculation to correct it, but I just feel more confident in the results of it.

In case you need it, here is a link to a temperature correction site.

Salinity Correction Calculator

Aquarium calculator; Correct a relative specific gravity (sg) measurement taken with a non-temperature-correcting unit.

www.hamzasreef.com

 

[Fish Fan]

I just wanted to add that I have had a great experience with my TM hydrometer. It has been my main measuring for salinity for the last year. I have used digital and refractometers and because they need to be calibrated and do drift I was always self guessing about its accuracy. A few negatives are that the hydrometer is a bit more cumbersome to use, it’s big, and it’s fragile, and if using in your tank all the pumps need to be turned off. Also, as you know if the water temp isn’t at its 77 calibrated degrees, you do have to use a calculation to correct it, but I just feel more confident in the results of it.

In case you need it, here is a link to a temperature correction site.

Salinity Correction Calculator

Aquarium calculator; Correct a relative specific gravity (sg) measurement taken with a non-temperature-correcting unit.

www.hamzasreef.com

Thank you for your help, I appreciate the info!

 

[Randy Holmes-Farley]

I just wanted to add that I have had a great experience with my TM hydrometer. It has been my main measuring for salinity for the last year. I have used digital and refractometers and because they need to be calibrated and do drift I was always self guessing about its accuracy. A few negatives are that the hydrometer is a bit more cumbersome to use, it’s big, and it’s fragile, and if using in your tank all the pumps need to be turned off. Also, as you know if the water temp isn’t at its 77 calibrated degrees, you do have to use a calculation to correct it, but I just feel more confident in the results of it.

In case you need it, here is a link to a temperature correction site.

Salinity Correction Calculator

Aquarium calculator; Correct a relative specific gravity (sg) measurement taken with a non-temperature-correcting unit.

www.hamzasreef.com

The “bit more cumbersome” of the hydrometer is exemplified by the difficulty in acclimating a new fish from low salinity, which is very easy with a drop in conductivity probe. :)

 

[Fish Fan]

The “bit more cumbersome” of the hydrometer is exemplified by the difficulty in acclimating a new fish from low salinity, which is very easy with a drop in conductivity probe. :)

I saw several of your previous posts where you said you prefer a conductivity probe. But wouldn't those also need to be calibrated regularly? In my case, I'm not feeling 100% confident in making your test standards with the $12 kitchen scale I have. For that reason, I'm leaning towards the hydrometer and a graduated cylinder to float it in. To me, this is the greatest peace of mind.

Out of curiosity, what conductivity meter do you recommend?

 

[edsbeaker]

The “bit more cumbersome” of the hydrometer is exemplified by the difficulty in acclimating a new fish from low salinity, which is very easy with a drop in conductivity probe. :)

That is especially true for me right now. I do not have a graduated cylinder and have to use mine in the DT or in my 55 gallon mixing container. I do have a fish in QT right now, and unfortunately it’s in a 10 gallon tank and the depth is not deep enough to use it. It certainly wouldn’t work with a fish in a bag either.

I really need to order a cylinder!

 

[Randy Holmes-Farley]

I saw several of your previous post where you said you prefer a conductivity probe. But wouldn't those also need to be calibrated regularly? In my case, I'm not feeling 100% confident in making your test standards with the $12 kitchen scale I have. For that reason, I'm leaning towards the hydrometer and a graduated cylinder to float it in. To me, this is the greatest peace of mind.

Out of curiosity, what conductivity meter do you recommend?

The ones I have used cannot be calibrated, and drift is minor to nonexistent (assuming one does not leave them in the tank water). Doesn't mean the actual readings are spot on, but it's a fixed correction. In any case, checking them in a diy standard is quick and easy. I made such a standard, bottled it, and can drop the probe in for a test any time.

Randy's Tank and Learn Thread

Ok will have to be tomorrow Sorry this took so long got sidetracked also have bumble bee snails which I rarely see because they get into the substrate, same for Trochus. But here are the Nassarius which clean your rock unbelievable changed mine from black to a weird green , but will also knock...

www.reef2reef.com

 

[BeanAnimal]

The ones I have used cannot be calibrated, and drift is minor to nonexistent (assuming one does not leave them in the tank water). Doesn't mean the actual readings are spot on, but it's a fixed correction. In any case, checking them in a diy standard is quick and easy. I made such a standard, bottled it, and can drop the probe in for a test any time.

Randy's Tank and Learn Thread

Ok will have to be tomorrow Sorry this took so long got sidetracked also have bumble bee snails which I rarely see because they get into the substrate, same for Trochus. But here are the Nassarius which clean your rock unbelievable changed mine from black to a weird green , but will also knock...

www.reef2reef.com

You had listed some viable models at one point. If I remember, you have some rather expensive devices?

 

[Ben's Pico Reefing]

Just wanted to point out a trick for those with eye problems and refractometers. You can use your phone lens to take a picture and zoom in. I have done this before to send an image. Just a tip.