Average Accuracy of Glass Hydrometers

[KStatefan]

why do you make so much Lol. I use 3.65 salt and 96.35 water.

How do you get your hydrometer to float in 100 ml of water?

 

[Reef.]

How do you get your hydrometer to float in 100 ml of water?

I hold it up, I’m cheap, salt is expensive.

I have just bought a veegee refractometer so had that on my mind as I’ve been checking that over the last few days.

 

[EricR]

why do you make so much Lol. I use 3.65 salt and 96.35 water.

There's also this:

The more you make, the less impact your salt measurement inaccuracy will have on the final result.

 

[Tcook]

I just picked up a precision scale from Amazon, no brand, seems very accurate, but could very well be slightly out, My thermometer is certified to within 0.1c, the thermometer plays a big part, the average thermometer can be out over 1 degree, that’s why I think it’s hard to say it’s your hydrometer that is out as much as you said it was, when it could be the scale,or thermometer.

I have one of the nist cert thermometers from BRS

 

[EeyoreIsMySpiritAnimal]

@livinlifeinBKK , I'm confident that you will find a solution that works for you. You're already ahead of the game by understanding that salinity arguably is one of the most important parameters (temperature being the other). Find a method that works for you, whether it's buying calibration fluid, making your own, getting a glass hydrometer, or a conductivity probe... as has been mentioned, being "off" a slight amount compared to natural saltwater is moot if you're able to maintain a consistent value in YOUR tank.

 

[livinlifeinBKK]

@livinlifeinBKK , I'm confident that you will find a solution that works for you. You're already ahead of the game by understanding that salinity arguably is one of the most important parameters (temperature being the other). Find a method that works for you, whether it's buying calibration fluid, making your own, getting a glass hydrometer, or a conductivity probe... as has been mentioned, being "off" a slight amount compared to natural saltwater is moot if you're able to maintain a consistent value in YOUR tank.

I think I'm gonna make my own calibration fluid...after several months I've just began to question the accuracy of my probe and since I just ordered a scale and bought some salt I think making my own calibration fluid will not only save a few bucks but possibly give me some comfort in knowing I didn't just receive a bad batch of calibration fluid factory produced...after I receive the scale and make the calibration fluid depending on how far off my probe is and the cost of a well reviewed glass hydrometer I can buy off Amazon I'll also go with a glass hydrometer for peace of mind since there are no moving parts. I appreciate you saying I'm ahead of the game by acknowledging the critic importance of stable and accurate salinity in our tanks!

 

[EricR]

I think I'm gonna make my own calibration fluid...after several months I've just began to question the accuracy of my probe and since I just ordered a scale and bought some salt I think making my own calibration fluid will not only save a few bucks but possibly give me some comfort in knowing I didn't just receive a bad batch of calibration fluid factory produced...after I receive the scale and make the calibration fluid depending on how far off my probe is and the cost of a well reviewed glass hydrometer I can buy off Amazon I'll also go with a glass hydrometer for peace of mind since there are no moving parts. I appreciate you saying I'm ahead of the game by acknowledging the critic importance of stable and accurate salinity in our tanks!

Someone surely posted this before but don't see it so...

Check out Randy's DIY calibration standards:

Homemade Salinity Standard

You have to do some reading but I'm having much better results since switching to his DIY EC (conductivity) standard. (He has standards for each of the different methods; refraction/SG/conductivity)

 

[livinlifeinBKK]

Someone surely posted this before but don't see it so...

Check out Randy's DIY calibration standards:

Homemade Salinity Standard

You have to do some reading but I'm having much better results since switching to his DIY EC (conductivity) standard. (He has standards for each of the different methods; refraction/SG/conductivity)

I certainly will! Thanks!

 

[Reef.]

I think I'm gonna make my own calibration fluid...after several months I've just began to question the accuracy of my probe and since I just ordered a scale and bought some salt I think making my own calibration fluid will not only save a few bucks but possibly give me some comfort in knowing I didn't just receive a bad batch of calibration fluid factory produced...after I receive the scale and make the calibration fluid depending on how far off my probe is and the cost of a well reviewed glass hydrometer I can buy off Amazon I'll also go with a glass hydrometer for peace of mind since there are no moving parts. I appreciate you saying I'm ahead of the game by acknowledging the critic importance of stable and accurate salinity in our tanks!

After you get your salinity checker of choice calibrated perfectly your ato will dump a load of rodi water into your tank or a snail will crawl over your overflow triggering your ato you’ll then wonder why you bothered trying to get your salinity correct!

 

[RichReef]

A TM glass hydrometer crashed my tank. Well I did because I was blind and irresponsible. I chased an ongoing problem for 9 months. Watched almost everything die on by one. Spent hundreds and hundreds of dollars.

Was at Petco and saw a refractometer for sale. Said what the heck I'll buy it.

My salinity was 1.035. Yes 1.035. Checked with TM hydrometer ... 1.025. Checked and rechecked. Checked again.

Started diluting the tank water by removing water and letting ATO top it off. With in 2 days my tank was booming. The very first thing I noticed was the explosion of pods.

I will never use anything but a refractometer calibrated with a solution from now on.

I posted a thread about what happened if you want the entire story.

 

[livinlifeinBKK]

A TM glass hydrometer crashed my tank. Well I did because I was blind and irresponsible. I chased an ongoing problem for 9 months. Watched almost everything die on by one. Spent hundreds and hundreds of dollars.

Was at Petco and saw a refractometer for sale. Said what the heck I'll buy it.

My salinity was 1.035. Yes 1.035. Checked with TM hydrometer ... 1.025. Checked and rechecked. Checked again.

Started diluting the tank water by removing water and letting ATO top it off. With in 2 days my tank was booming. The very first thing I noticed was the explosion of pods.

I will never use anything but a refractometer calibrated with a solution from now on.

I posted a thread about what happened if you want the entire story.

I fully plan to test the hydrometer against homemade calibration fluid to avoid anything like that from happening

 

[livinlifeinBKK]

I've definitely read some negative reviews about them as well...I think it's safe to say any salinity measuring device needs to be checked against others and it'll never be perfect due to standard error like I mentioned earlier but some are definitely closer than others... refractometers seem to be the highest rated by far on Amazon. @Randy Holmes-Farley I know you have a method of making a stock 35 PSU solution but I've also heard from a pretty reputable source that one can be made simply from weighing 35 grams of table salt and mixing it into a 1 liter bottle of water as bottled beverages are usually very close to the stated volume (I've heard a 1 liter bottle of alcohol is actually practically exactly 1 liter due to being taxed for every drop of alcohol (of course the liquor bottle would be emptied and filled with RODI water before mixing the salt.) Is that true? Also are salinity refractometer calibration fluids really as unreliable as people have said?

Hey @Randy Holmes-Farley are these true statements I tagged you in earlier?

 

[Randy Holmes-Farley]

Hey @Randy Holmes-Farley are these true statements I tagged you in earlier?

Sorry, missed those incorrect statements. Lol

my recipes show exactly how much table salt is needed to make 35 ppt standards for all the devices we use. Each is different and none are 35 g/L.

Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com

 

[BVF]

My TM hydrometer reads high by .003 PPT at 77f, so my salinity was low for a while, down around 1.022 while I thought I was dialed in at 1.025. I used Brightwells and made 2 separate batches of Randy Holmes’ solution, comparing it against 2 Icecap digital testers. It took a while to trust anything again.

My Icecaps still read crazy sometimes. How does it read 1.021, I add more salt and a minute later it reads 1.018?

 

[Sasquatchv]

I really like the idea of the glass hydrometer but the Tropic Marin one isn't available anywhere I can find since I'm not in the States which leaves me with other options on Amazon but people aren't personally vouching for them because they haven't used them. Also, if I don't go with the Tropic Marin one (I don't know how I can) or a really expensive individually calibrated one I found on Amazon I have to buy the calibration fluid anyway to test for deviations so I might as well just go with the calibration fluid for now because why would I need a well calibrated refractometer and a hydrometer at the same time?

I bought this one:

tested against calibrated red sead refractometer in my LFS 0.0005 out.
Now i have knwn non perishable "standard" at home

 

[Reef.]

My TM hydrometer reads high by .003 PPT at 77f, so my salinity was low for a while, down around 1.022 while I thought I was dialed in at 1.025. I used Brightwells and made 2 separate batches of Randy Holmes’ solution, comparing it against 2 Icecap digital testers. It took a while to trust anything again.

My Icecaps still read crazy sometimes. How does it read 1.021, I add more salt and a minute later it reads 1.018?

The temp reading could be what if off, they can be out as much as 1-2 degree, that would affect the reading, or the scales, to put the 0.003 down to the hydrometer is unfair.

 

[Sasquatchv]

The temp reading could be what if off, they can be out as much as 1-2 degree, that would affect the reading, or the scales, to put the 0.003 down to the hydrometer is unfair.

0.003 ppt is like a pinch of salt to 10 gallons.
Unless he means 0.003sg...
0.003sg error would mean 10c or 18F temperature error/difference from calibrated temperature.
I.e: hydrometer calibrated at 70F and water measured at 88F will result in sg readin 0.003 lower than actual.

 

[Reef.]

0.003 ppt is like a pinch of salt to 10 gallons.
Unless he means 0.003sg...
0.003sg error would mean 10c or 18F temperature error/difference from calibrated temperature.
I.e: hydrometer calibrated at 70F and water measured at 88F will result in sg readin 0.003 lower than actual.

The TM hydrometer reads to 4 decimal places, I was taking it as 0.0003, I doubt the hydrometer is off by 0.003, I would put that down to user error, or as said the temp or scales but it is possible the hydrometer is that much off but I would check other more likely cause for the reading first.

 

[Syntax1235]

I’ve had the same TM hydrometer for over 20 years and it has served me well. I have to calibrate my Refractometer each time I use it. I find they both have their uses - TM for freshly mixed sw, Refractometer for checking the display and qt. When checked against each other they always display the same reading. Once in a while the refractor reads high if there is some salt residue on the glass before calibrating. After cleaning it with RO it reads what the TM reads.