What is better, a Refractometer or a Hydrometer?

[miogpsrocks]

What is better, a Refractometer or a Hydrometer?

I tried to look up info on the Refractometer and its a lot of beer making applications. Are those the same one used in salt water Aquariums?

Thanks.

 

[bundybear1981]

A refractometer is a far more accurate and reliable instrument. Although they are used in beer making (among other purposes) the are not interchangeable.

There are some differences in them and their scales of measure. You just need to make sure when you buy one it is for salt water use and to pick up some calibration fluid for it.

Using RODI to calibrate is doable however the further your 'end point' is from the calibration mark the higher % of drift can occur. If you check one of the sponsor sites (such as bulk reef supply) they have suitable one there.

 

[miogpsrocks]

A refractometer is a far more accurate and reliable instrument. Although they are used in beer making (among other purposes) the are not interchangeable.

There are some differences in them and their scales of measure. You just need to make sure when you buy one it is for salt water use and to pick up some calibration fluid for it.

Using RODI to calibrate is doable however the further your 'end point' is from the calibration mark the higher % of drift can occur. If you check one of the sponsor sites (such as bulk reef supply) they have suitable one there.

I am glad that you told me because I almost purchased one of the beer ones. It was measured in brix or something.

 

[Happyschneider]

The big advantage of refractometer is that they give you a temperature independant reading. That means you can test your water independently of the temp the water is at and can compare to other water (for example freshly mixed water for water changes before brought to the exact temp).

Always rinse with RO/DI directly after use and dry with paper towel and as stated above calibrate regularly. Then it is extremely reliable.

Another tip, make sure the entire area is covered with liquid without any bubbles. My experience is to use either natural light or light with low blue (not too close to the aquarium with all those actinics) and a light source above your head. If the line seems fuzzy, try changing the angle so that the glass area is as level as possible, that should help making the line as sharp as possible.

 

[Ron Reefman]

Despite what you have read here. If you are on a budget, a hydrometer is perfectly acceptable tool. They get a bad rap here from people who are too critical and who like to spend money on techno-toys.

First thing is that absolute salinity level isn't that critical and maintaining a stable level is only slightly more important.

Second, a refractometer is more accurate, but in no way is it more reliable! I have both and here is what I did. I took my refractometer and calibrated it (yes, they need to be calibrated every so often, I did mine every 6 months). Then I tested my aquarium water and it was 1.025, OK. Then I took my hydrometer and tested the same water and it was 1.026. Well, that difference is next to nothing. But I put a label on my hydrometer that says "reads 0.001 HIGH". So for 3 years now I have calibrated my refractometer every 6 months and it is always a little off, so I adjust it. Then I test my water and then do the same test with the hydrometer. And EVERY time the hydrometer reads 0.001 higher than the refractometer.

Moral of the story... yes a CALIBRATED refractometer is more accurate than a hydrometer. But it is NOT more reliable. I never have to do anything to the hydrometer but rinse it and shake it dry after I use it. No calibrating, no BS, just subtract 0.001 from the reading and I'm good.

I've done this for a couple of friends as well. Their hydrometers have their own "error" rate, but every time we test them, the error is always the same.

So buy a hydrometer, or get one free from a friend in the hobby. Then find somebody (or an LFS) with a good CALIBRATED refractometer and compare it's readings with your hydrometer and put a label on it to remind you of the error rate.

 

[Bent]

FWIW

I measured 35ppt saltwater (using a calibrated refract) in the following:

Uncalibrated refract just opened
Floating glass hydro
Three 10+ year old swing arm hydros I had laying around that have been God knows where.
A brand new swing arm hydro

Everything except the Uncalibrated fresh out of the box refract was correct...

Take that for what you will.

 

[kmbyrnes]

I will not dispute the experience of others. My own experience is that in the past year my eyesight is 'showing its age' and I find the ability to focus the refractometer to fit my vision is quite helpful. I calibrate mine every time I think about it ( like now ). But so far it has never been off by more than .001.
When I started in the hobby, everything was new and unknown. I questioned every step I took. With experience, I can now get my salinity almost spot on during the mixing process. Nonetheless, I test my WC water and tank salinity every couple days.
Continue to ask questions, but remember you will get different opinions. Most of the time, if there are multiple posts advocating one method or another, both will be acceptable and just a matter of personal preference.

 

[jrp1588]

Get the cheap ~$30 refractometer at Bulk Reef Supply. It comes with calibration fluid if I remember correctly. Though, in all the times I've calibrated, it's never needed it.

 

[cloak]

Despite what you have read here. If you are on a budget, a hydrometer is perfectly acceptable tool. They get a bad rap here from people who are too critical and who like to spend money on techno-toys.

+1

I've been using a cheap $7.99 floating glass hydrometer for the past 17 years or so without any problems. My parents use to use a floating glass hydrometer on their tank back in the late 70's early 80's as well. Here it is almost 2016 and this same design can be found at pretty much any reputable LFS around the globe. It just goes to show that these things do in fact work, quite well actually. GL.

Perfect!

 

[Rhygar666]

i bought a big hydrometer from tropic marine thats easy to read and i havent been dissapointed, tough i like the digital refracs and one day when i swim in money i will get one, till then im happy with my hydro

 

[reefwiser]

Milwaukee digital refractometer [emoji106]

 

[KingTriton1]

Milwaukee digital refractometer [emoji106]

^Agreed

 

[heritage]

Obviously the refractometer is the way to go. You can get one with a bottle of calibration fluid for under $50. Spend a few seconds every month calibrating it and you'll never have a problem. Nothing wrong with using any of the other instruments, but you still need a refractometer to check that the reading is right.