Not sure if i call it chemistry, but Hydrometer issue

davered00ss

davered00ss

New member
I set up a new biocube 32, and have 2 hydrometers. one is instant ocean and is reading 1.030. the other is a cheap floating type and reads 1.022 with filter and power head off.

When put in D.I. water cheap one is right on 1.000, instant ocean one is 1.004

we have a lab where I work, and I plan to weigh the water tomorrow and get a real number. I just don't want to do this all the time.

Do I really need to purchase a refractometer (sp) ? From what I have read they are kind of difficult to calibrate.

Or use another type of hydrometer.

I did clear the bubbles of the instant ocean hydrometer needle.
 
well.. you really don't need a refractometer once you can verify your hydrometers accuracy.. They seem to stay consistent forever/long time. (be it consistently high or low,etc..)
But a refractometer isn't hard to calibrate either and does add a little extra piece of mind..
I just drop a few drops of the calibration solution on it and turn a screw as needed to calibrate it..
 
you can use randys calibration fluid to find out where its inaccuracy lies. Mine reads about .001 low. 1.025 is actually 1.026.
 
You probably can calibrate the swing-arm with a saltwater standard, like the PinPoint Salinity Calibration Fluid. Personally, I went with a conductivity meter since it's a bit more flexible than a refractometer, but either of those types of devices probably would be easier to use. They are easy to calibrate, in my experience, as well.
 
Throw it away and the 30 bux. Its just another Better way of reading.However, I used one for years and like mcgyvr says was a longtime standard. It's just that if you even get a micro bubble under the swing arm you're looking at the wrong gravity. As I said one reads specific gravity and the refractometer determines displacement, a hydrometer density.

Sent from my SM-G930V using Tapatalk
 
I have a little plastic piece that I stick in my swing arm to bang it around and dislodge it/knock off any bubbles. After using it for years and knowing the calibration, Im fairly sure that salinity is spot on.

I would like to have a refractometer, though. Do they get knocked out of adjustment and need calibration often?
 
bertoni said:
You probably can calibrate the swing-arm with a saltwater standard, like the PinPoint Salinity Calibration Fluid. Personally, I went with a conductivity meter since it's a bit more flexible than a refractometer, but either of those types of devices probably would be easier to use. They are easy to calibrate, in my experience, as well.
Click to expand...

What reading are you looking for on the conductivity meter? I have a Hach portable one in my office at work that is not in use lol and calibration standards for it. :lmao:
 
I manage a wastewater treatment plant for a small city. We have a pretty decent lab on site to test water and wastewater. its easy to bring in water to work and test it, or borrow equipment overnight :)
 
Take in a sample of your water and your hydrometer. Test the water with your lab equipment. Lets just say it tests at 1.026. Then test the water with your hydrometer and lets say it reads 1.030. Then you'll know the hydrometer reads 0.004 too high. Mark your hydrometer (I put a label on mine) so you know the hydrometer reads 0.004 too high. I made the label say, "subtract 0.004". If you feel this isn't enough, the next time the salinity in your tank is different, test it like this again. I'll bet you'll find the hydrometer is off by the same 0.004 as it was in the first test.

I have a refractometer and calibration fluid as well as 2 hydrometers. I did this test about 5 years ago and did the retest every 3 months for a year and then twice a year for the next 2 years. I recalibrated the refractometer each time. BTW, sometimes it needed the calibration and sometimes it didn't. But both hydrometers had the very same error rate they had in the first test. Never failed, always the same.

Personally I find the hydrometer easier to use and now I never consider if it is right or wrong. I know it's right. And if I test with the refractometer and it's different than the hydrometer, then I test it with the calibration fluid and guess what? I find that it's out of calibration and the cheap hydrometers were right!
 
Although I check my refractometer nearly every time I use it, I rarely find it off. I actually only ever have to calibrate it whenever I drop it, or it gets a hard bump. It'sa typically spot on 99% of the time.

I used to use a hydrometer too, there is just way to many variables at play for them to be as accurate as a properly calibrated refractometer.

Or as Ron suggested, use one to calibrate the other.
 
Looks like the Instant Ocean Hydrometer was right. After weighing 100 ml of water, I came up with a specific gravity of 1.0327

Looks like I need to add some D.I. Water to the tank.
 
Be careful when measuring the volume of the water to check the SG. you need to be able to measure the volume very accurately in order to determine this, and most graduated cylinders are +-5%. I even just got a set of nice calibrated ones used to calibrate other cylinders and they aren't even accurate enough to determine SG to the level I would want.

This can be done with the right equipment though. I have an extreamaly sensitive scale in my lab (resolution 0.00mg) and I use it with a graduated cylinder to weight out 100g of DI water, then note exactly what the cylinder says the volume is. Then I empty and dry the cylinder, and fill it to the same exact volume I recorded before and weigh again. This provides an accurate SG for the fluid.

In order to measure to 1.0264 SG +-0.0001 you need all measurments to have less than 0.01% error cumulatively. Just keep that in mind if that's a route you want to take.

I just recently switched from my swing arm to a refractometer. I'm very happy with the switch as I have more confidence in the repeatability of the refractometer, even if you do need to check it's calibration frequently, it's very easy and quick to do, and no worries about micro bubbles or anything like that.
 
Ron Reefman said:
Take in a sample of your water and your hydrometer. Test the water with your lab equipment. Lets just say it tests at 1.026. Then test the water with your hydrometer and lets say it reads 1.030. Then you'll know the hydrometer reads 0.004 too high. Mark your hydrometer (I put a label on mine) so you know the hydrometer reads 0.004 too high. I made the label say, "subtract 0.004". If you feel this isn't enough, the next time the salinity in your tank is different, test it like this again. I'll bet you'll find the hydrometer is off by the same 0.004 as it was in the first test.

I have a refractometer and calibration fluid as well as 2 hydrometers. I did this test about 5 years ago and did the retest every 3 months for a year and then twice a year for the next 2 years. I recalibrated the refractometer each time. BTW, sometimes it needed the calibration and sometimes it didn't. But both hydrometers had the very same error rate they had in the first test. Never failed, always the same.

Personally I find the hydrometer easier to use and now I never consider if it is right or wrong. I know it's right. And if I test with the refractometer and it's different than the hydrometer, then I test it with the calibration fluid and guess what? I find that it's out of calibration and the cheap hydrometers were right!
Click to expand...

i have been saying this all along. Consistence is the most important part , If you use a hydrometer the same each time.. You will get correct results each time.Thou they may a bit off actually scientific exact results..

If you use a refractormeter that you do not keep calibrated you will get results that will very..

the cheaper of the two is much more accurate.. As you have done just confirm where it stands against scientific exact results and be done with it...

the only benefit of using refractometer is .. ohh nevermind...
Thank you.....
 
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