Which to believe...Milwaukee Refractometer or Tropic Marin High Precision Hydrometer?

[Reef.]

Did you compensate for temperature using the hydrometer?

And how accurate was the thermometer used? Most can be off by a lot.

 

[Dburr1014]

This question was asked and answered yesterday in this thread. Try and keep up!

Uncalled for.

 

[Dburr1014]

No. I don't think so.

Sorry, I missed that post.
I'm very surprised it was off.
Was it new? Any noticeable damage?

 

[RichReef]

Sorry, I missed that post.
I'm very surprised it was off.
Was it new? Any noticeable damage?

I bought it new when I started the tank in 2013. It was ... I believe accurate at the start. I didn't have a problem until 2017. 4 years. I used a graduated cylinder when testing. There was no indication of damage. Same brand of salt the entire time. I wish I could explain it better. I think I may still have it tucked away somewhere. If I can find it I will take a closer look and maybe even test it again and take a video. But I have to find it. I do not remember throwing it away.

 

[RichReef]

Sorry, I missed that post.
I'm very surprised it was off.
Was it new? Any noticeable damage?

I don't mean to take a dig at the TM Hydrometer. I have been around long enough to know it's considered the best by many in the hobby which is why I purchased it at the start. I am trying to say don't just blindly trust it. Test it every now and then.

 

[Tcook]

I bought it new when I started the tank in 2013. It was ... I believe accurate at the start. I didn't have a problem until 2017. 4 years. I used a graduated cylinder when testing. There was no indication of damage. Same brand of salt the entire time. I wish I could explain it better. I think I may still have it tucked away somewhere. If I can find it I will take a closer look and maybe even test it again and take a video. But I have to find it. I do not remember throwing it away.

Yes. Test it with Randys standard. I wonder if the paper scale inside the hydrometer moved?

 

[mckinney0171]

Don’t mean to hijack - but does anyone have a link to a good quality scale from amazon? I bought a digital one a while back and it was a Chinese piece of crap. Had good reviews of course. I can never get it to repeat a measurement and it shuts off on its own.
I want to make Randy’s recipe to check calibration on my refractometers.

 

[Tcook]

Don’t mean to hijack - but does anyone have a link to a good quality scale from amazon? I bought a digital one a while back and it was a Chinese piece of crap. Had good reviews of course. I can never get it to repeat a measurement and it shuts off on its own.
I want to make Randy’s recipe to check calibration on my refractometers.

I bought this one

 

[RichReef]

Yes. Test it with Randys standard. I wonder if the paper scale inside the hydrometer moved?

That may be quite possible. I will admit I didn't pay much attention to what went wrong. I was just happy things got moving in the right direction.

 

[BeanAnimal]

Read above. I'm not repeating it.

I did not see you prior post. A polite "Please see post above" would have sufficed.

They are extremely accurate instruments. I would lean toward either user error or the extremely remote possibility that you had a defective hydrometer, or the wrong model.

TM makes at least two models. Do you remember the color of the scale? Blue or Green?
One is calibrated for sg and the other density.

Many refractometers, calibrated or not with ATC or not... are just not that accurate (can be wildly off), the same with swing arms.

By all means, use whatever you are comfortable with and is proven by your tank results and personal experience.

I have a TM hydrometer and have checked it against a standard. I have (3) refractometers of different brands and physical makes, a profilux with conductivity, a Milwaukee digital and the TM.

2 of the three refractometers are the same. One varies with seawater even if calibrated side-by-side with calibration solution.

They don't match the Milwaukee or the P4 or the TM

The P4 does not match anything

The Milwaukee does not match anything.

So 6 devices, 5 different seawater readings of the same sample that EASILY vary from ~32 PSU to ~37 PSU when the TM reads 35 PSU at calibrated temperature.

- I verified the TM so use it as a baseline. This is the gold standard (for me)
- I mentally compensate for the P4 (the chart/dashboard I look at daily) when looking for drift.
- I don't use the Milwaukee - it is hunk of crap
- I use the refractometer(s) when acclimating. I don't care if it is "accurate" as long as it is repeatable. That is, If the tank reads 1.2345 on it then I know that my acclimation water needs to be brought to 1.2345 before dumping the fish in.

 

[BeanAnimal]

I bought this one

You have to be careful with cheap scales...

They may have 70 digits after the decimal place and the scale may be in billionths of a gram... but the accuracy may be to the nearest gram and the error +/- a gram even if the marketing says the $10 scale is .001g accurate. All of the digits after the decimal being insignificant eye candy.

 

[BeanAnimal]

I bought it new when I started the tank in 2013. It was ... I believe accurate at the start. I didn't have a problem until 2017. 4 years. I used a graduated cylinder when testing. There was no indication of damage. Same brand of salt the entire time. I wish I could explain it better. I think I may still have it tucked away somewhere. If I can find it I will take a closer look and maybe even test it again and take a video. But I have to find it. I do not remember throwing it away.

It may be possible that a tiny crack let water in or maybe somehow the paper scale in the next moved... who knows.

It would be interesting if you did find it and inspect/test it again.

 

[Bruce Burnett]

It forces you to calibrate with RO/DI, I think, but then you can always check it with a 35 ppt standard.

What I have done for years. You also have to flush the the little bulb pipette with tank water every time. If you let it dry with saltwater drops still in it you will get a high reading. Also very important to clean the lens. You should be able to do a test and get the same results 3 times in a row.

 

[BeanAnimal]

My Milwaukee is pure garbage. It is sometimes correct, but often won't even calibrate correctly and throws errors about the sample. On the list of the worst reef investments that I have ever made.

 

[Tcook]

You have to be careful with cheap scales...

They may have 70 digits after the decimal place and the scale may be in billionths of a gram... but the accuracy may be to the nearest gram and the error +/- a gram even if the marketing says the $10 scale is .001g accurate. All of the digits after the decimal being insignificant eye candy.

Yes but no one here is going to shell out for a sartorius. You can order a set of standard weight to test the accuracy. I may try that out.

 

[jimk60]

I did not see you prior post. A polite "Please see post above" would have sufficed.

They are extremely accurate instruments. I would lean toward either user error or the extremely remote possibility that you had a defective hydrometer, or the wrong model.

TM makes at least two models. Do you remember the color of the scale? Blue or Green?
One is calibrated for sg and the other density.

Many refractometers, calibrated or not with ATC or not... are just not that accurate (can be wildly off), the same with swing arms.

By all means, use whatever you are comfortable with and is proven by your tank results and personal experience.

I have a TM hydrometer and have checked it against a standard. I have (3) refractometers of different brands and physical makes, a profilux with conductivity, a Milwaukee digital and the TM.

2 of the three refractometers are the same. One varies with seawater even if calibrated side-by-side with calibration solution.

They don't match the Milwaukee or the P4 or the TM

The P4 does not match anything

The Milwaukee does not match anything.

So 6 devices, 5 different seawater readings of the same sample that EASILY vary from ~32 PSU to ~37 PSU when the TM reads 35 PSU at calibrated temperature.

- I verified the TM so use it as a baseline. This is the gold standard (for me)
- I mentally compensate for the P4 (the chart/dashboard I look at daily) when looking for drift.
- I don't use the Milwaukee - it is hunk of crap
- I use the refractometer(s) when acclimating. I don't care if it is "accurate" as long as it is repeatable. That is, If the tank reads 1.2345 on it then I know that my acclimation water needs to be brought to 1.2345 before dumping the fish in.

I agree, I found myself in the same situation with all my different devices. Every time i bought something new I found out I really couldn't keep it calibrated. I went with the TM and haven't looked back. Never even checked it as everything looks happy. I figured at least it's consistent.

 

[MiniCoco]

Hi all. Wondering what you'd do...

My new Tropic Marin High Precision Hydrometer is reading my tank at 1.0235 SG while my Milwaukee Refractometer is reading 1.022. What gives? The Milwaukee was calibrated as instructed with RODI water (direct from my new BRS 5 Stage Premium Plus 150 GPD Water Saver RO/DI System). I've heard the Hydrometer is the ultimate in precision, but it's recommended to get the milwaukee for convenience (and accuracy). What would you do in this situation? Thanks!

Hydrometers tend to be more accurate as long as your technique is solid. The Milwaukee Instruments unit is well made, but will require occasional calibration. The main concern for hydrometers is they will not take too much abuse.

 

[BeanAnimal]

Hydrometers tend to be more accurate as long as your technique is solid. The Milwaukee Instruments unit is well made, but will require occasional calibration. The main concern for hydrometers is they will not take too much abuse.

My Milwaukee does not calibrate easily and even calibrated before every use, using a light cover and ensuring a clean sample cup... is all over the map. To me it is a toy, not an instrument. Maybe I have a bad one... but am not about to buy a second one.

 

[Tcook]

The Milwaukee is like a one-armed-bandit. You keep pushing the read button until you get a value you like. Mine is under the sink. I spot check with an Aquarium Solutions swing are that I calibrated with the TM.

 

[Miami Reef]

The Milwaukee is like a one-armed-bandit. You keep pushing the read button until you get a value you like. Mine is under the sink. I spot check with an Aquarium Solutions swing are that I calibrated with the TM.

Haha! This is so relatable!