Swing arm salinity tester needs to condition in saltwater for 24 hours?

[rav3n]

I recently purchased a Fluval swing arm salinity or specific gravity tester. Upon using it my salinity was perfect 1.023 on my first few tests. After it sat overnight in saltwater and I tested again it was 1.019 24 hours later?! Is it expected that a new gauge will read different after it sits in saltwater for 24 hours as Ive read?

Note: I did not change any water or anything in the tank.

[downbeach]

Originally Posted by rav3n

I recently purchased a Fluval swing arm salinity or specific gravity tester. Upon using it my salinity was perfect 1.023 on my first few tests. After it sat overnight in saltwater and I tested again it was 1.019 24 hours later?! Is it expected that a new gauge will read different after it sits in saltwater for 24 hours as Ive read?

My suggestion is to get a decent refractometer, and a seawater calibration solution if it doesn't come with it. Swing arm type hydrometers can be both inaccurate an inconsistent with the readings.

[MondoBongo]

when you say that it sat in saltwater overnight then gave a different reading, was the water temperature the same for both readings?

i haven't used a swing arm hydrometer for a few years now, but i know my refractometers are supposed to be calibrated for a specific temperature range.

-edit- i too would advise you get a decent refactometer. they make life way easier.

[D-Nak]

Originally Posted by downbeach

My suggestion is to get a decent refractometer, and a seawater calibration solution if it doesn't come with it. Swing arm type hydrometers can be both inaccurate an inconsistent with the readings.

+1. For the amount of time and money invested in our tanks, it's not worth relying on a cheap swing arm hydrometers. Even the floating ones are probably better.

I test my salinity a lot, and if you're lazy like me, get one of these:

http://www.bulkreefsupply.com/milwau...actometer.html

I bought mine on during black friday and saved a lot of money.

To answer your original question, I would rinse the hydrometer with fresh water, let it dry completely, then test again. It should bounce back to normal. But again, even the smallest bubble stuck to the arm will cause it to read inaccurately.

[joshky]

Originally Posted by D-Nak

+1. For the amount of time and money invested in our tanks, it's not worth relying on a cheap swing arm hydrometers. Even the floating ones are probably better.

I test my salinity a lot, and if you're lazy like me, get one of these:

http://www.bulkreefsupply.com/milwau...actometer.html

I bought mine on during black friday and saved a lot of money.

To answer your original question, I would rinse the hydrometer with fresh water, let it dry completely, then test again. It should bounce back to normal. But again, even the smallest bubble stuck to the arm will cause it to read inaccurately.

I almost pulled the trigger on one of these myself, but it can be off by +/- 0.002 from factory and that's considered OK, that scares me.

[GimpyFin]

The Milwaukee digital refractometers are excellent. You'll spend close to $100, but they're well worth the money and make testing a snap. You also just calibrate it with RO/DI or distilled water, so you don't need a calibration solution like you do with the regular refractometers.

[rav3n]

Originally Posted by MondoBongo

when you say that it sat in saltwater overnight then gave a different reading, was the water temperature the same for both readings?

i haven't used a swing arm hydrometer for a few years now, but i know my refractometers are supposed to be calibrated for a specific temperature range.

-edit- i too would advise you get a decent refactometer. they make life way easier.

The water temperature was same for both reading. Even if the lights went off and the water cooled a bit (which I didnt see) and I tested again midday with the light blasting, it still was reading at 1.019.

It sounds like Im going to invest into a refactormeter . Thanks a lot for the suggestions !

[Mishri]

I used a swing arm for years before getting a refactometer.

here is an article on how to test your hydrometer (it's near the bottom) and it explains how to use it accurately.

http://www.reefkeeping.com/issues/2004-06/rhf/index.php

And yes, many do take 24 hours to soak to start providing accurate readings.

and using a refactometer is much better.. better peace of mind... I used RO/DI water to calibrate my refactometer, and after getting solution realized I was reading lower than actual, I had calibrated to the bottom of the 0 line, which was thick, and after using the solution and adjusting I saw that it needed calibrated to the top of the 0 line. It was about .002 low. Not a huge deal.. I was just at 1.023 when I thought I was at 1.025.. didn't hurt anything. Some people on here recommend calibrating every time but In many years I've never seen my refactometer change/be off. I'll test it maybe once a year.

[Ou8me2]

Personally, I would have spent a few dollars more and gotten a refractometer. You can find them on Ebay or Amazon for around $20.00 and get some calibration solution. It will be money well spent IMHO.

[disc1]

After it sat, were there bubbles on the arm?

[fishchef]

I used a swing for a long time. Used to take it into the LFS and test their water to compare for accuracy. Easier than a hydrometer. Went to a refractometer eventually and never looked back.