Hydrometer?

[John Biddle]

Seems like everyone uses the newest high tech refractometers rather than the old school float level hydrometer devices that are much cheaper, don't need calibration and are easy (easier?) to use. I'm getting back into the hobby from decades ago and I'm very pleased to see all the advances in reefkeeping. But this one needs explaining. Anyone care to clue me in?

 

[Brad Miller]

I’ve been using refractometers for many years in my trade to test oil, glycol and other mixes.
The ones they sell for saltwater specific gravity are cheap and very reliable, super easy to calibrate when need too.

Reliability and better accuracy

 

[John Biddle]

I know we're not talking about much of a difference money-wise, but just on this forum there are MANY posts of people complaining about their refractometers going out of caliber and causing them problems. Doesn't seem likely that a simple hydrometer like the Instant Ocean one or equivalents would do that. Yet no one seems to use them anymore.

 

[brandon429]

I do use swingarms vs refracts and will never change. Here’s mine, I have to guess where .o23 is

I don’t know how old this is, suspected 2011. Calibrates to .024 on a lfs refract, registers as .o23 here so that’s good nuff.

Got yall through the 80s 90s

 

[Brad Miller]

Most refractometers we use will have ATC (Automatic Temp Compensation) meaning that when you place it where you will be using it and give it time to adjust to that areas temperature, the sliding scale will move to compensate.

Sure, you can use the old one you used for your 1955 Desoto, but it would be near as accurate.
We like to see a consistently accurate and steady salinity for the more delicate and sensitive coral.

 

[clm65]

I still use one when mixing salt water to get me in the ball park. As I get close to target I will switch to the Milwaukee digital one.

FYI, mine is about 15 years old and when I compared its reading against the Milwaukee a few months ago, it was pretty darn close.

 

[reefwiser]

Swing arm testers will change over time. They are not accurate. It was found over time that they change and caused people to have lower salinity than the devices actually where showing. This caused issues with coral and fish health. As we progressed we realized this. I use refractors both visual and digital. Because they are easy to use and fast for testing.

 

[jd371]

I still use one when mixing salt water to get me in the ball park. As I get close to target I will switch to the Milwaukee digital one.

FYI, mine is about 15 years old and when I compared its reading against the Milwaukee a few months ago, it was pretty darn close.

I do the same. I only use it when mixing water and switch to a refractometer when getting close to the target salinity.

 

[LadyMac]

I use one for now but will be getting a refractometer soon.

 

[Florida Sunshine]

If cleaned and stored properly (upside down) they are known to be consistent. I would advise checking it against another device at least initially since sometimes they are off by a certain amount. So yours may read 1.023 and a refractometer reads 1.025 it is likely that all of your results from that hydrometer will be off by .002 consistently. Once you know what yours reads, you can adjust accordingly.
With a swing arm you want to be sure to rinse after each use and store upside down. Then be certain you have no bubbles when reading. If not stored properly, then salt can build up on the swing arm and cause your results to be off.

 

[W1ngz]

The reasons why:

Swing arms are impossible to clean properly. Eventually they will build up some salt crud. Salt crud will pull the arm down, reading lower.

They are prone to getting micro bubbles that stick to the swing arm, which cause your reading to trend higher.

Decades ago (so I've read) it wasn't possible to keep anything but the simplest corals alive. What was an acceptable reading for salinity back then? 1.026 + or - .003? Since that time all of us comparatively 'new' reefers who came along over the last 5-10 years benefit from access to far more and better information about water parameters beyond just salinity.

Consistency is key, and just being 'in the ballpark' doesn't cut it for most of the animals people can keep now. No successful reefer that I know of would accept ballpark salinity measurements between 1.022 and 1.030. I want 1.026 and I want all the rest of my parameters to be in lock-step with it.

 

[KStatefan]

Tropic Marin Hydrometer

 

[alton]

I love my Tropic Marin Hydrometers. The only change in the last ten years has been the blue topped out at 1.025, where new it starts at 1.025 and tops out at 1.027. I am guessing since we now use 35ppt as the standard which is 1.0264 specific gravity?