instant ocean swing arm hydrometer question

[j86miu]

Does anybody know if the reading from this hydrometer is affected by temperature?

I thought I read a review saying that the readings were independent for a temperature range of 60-85 degrees.. or something like that.:confused:

So I just wanted to make sure before I started correcting for temperature differences when reading the test data.

This site looks pretty useful for that:
http://www.algone.com/aquarium-articles/saltwater-aquarium/saltwater-salinity

[thegrun]

While I think for accuracy and reliability you are much better off using a refractometer, Instant Ocean hydrometers are temperature-corrected for use between 68° and 85°F.

[WhoDey64]

Given a normal house temp (75ish) its going to read fine. I have found them to always be very near my readings on a refractometer, just make sure you dont have any microbubbles trapped on the swing arm, that will screw with your readings.

[j86miu]

THanks guys - I ordered a refractometer since I was getting worried about the readings since I'm looking to add a toadstool mushroom. I just want to make sure nothing croaks because of bad hydrometer readings.

[disc1]

Yes, they are definitely affected by temperature.

[asid61]

I would get a cheap $25 refractometer from reefcleaners.org. It is the one that I have now. A month ago I used an instant ocean hydrometer, relatively new, about a month old. However, my corals kept on dying. I checked my params, and averything was fine and salinity at 1.026, or ~35 ppt. I got a refractometer, calibrated it, and what did I find? My hydrometer was reading 0.002 low(4ppt). My actual salinity was 1.028.
I lost about $50 in dead corals, because I used a hydrometer.

[1carpenter]

Only had experience with the more expensive refractometers not sure if they are all equal or not? But anyone is much better than a swing arm.

[Ron Reefman]

If you can calibrate your swing arm like you do regularly with your refractometer, the swing arm hydrometer can be just as accurate and they are less likely to get out of wack. I have a hydrometer that I tested to a freshly recalibrated refractometer. It was reading high by 0.002. That was over 2 years ago and I have recalibrated the refractometer about 8 times now (once per quarter) and then compared it to the hydrometer. The swing arm hydrometer never changes, it's alway reading 0.002 high. So if you know the error in your swingarm, it can work just fine!

[zigzag1]

If you can calibrate your swing arm like you do regularly with your refractometer, the swing arm hydrometer can be just as accurate and they are less likely to get out of wack. I have a hydrometer that I tested to a freshly recalibrated refractometer. It was reading high by 0.002. That was over 2 years ago and I have recalibrated the refractometer about 8 times now (once per quarter) and then compared it to the hydrometer. The swing arm hydrometer never changes, it's alway reading 0.002 high. So if you know the error in your swingarm, it can work just fine!

I use my hydrometer and refractometer in a similar way to Ron and reccommend this method also. I recalibrate my hydrometer using my refractometer when doing my full monthly testing of tank parameters. My hydrometer takes a beating that I wouldn't want to put on the device I use to set my 'standard' measure. My refracometer is over 10 years old and still looks and works like brand new. JMTC & GL!

[gnasher]

I would get a cheap $25 refractometer from reefcleaners.org. It is the one that I have now. A month ago I used an instant ocean hydrometer, relatively new, about a month old. However, my corals kept on dying. I checked my params, and averything was fine and salinity at 1.026, or ~35 ppt. I got a refractometer, calibrated it, and what did I find? My hydrometer was reading 0.002 low(4ppt). My actual salinity was 1.028.
I lost about $50 in dead corals, because I used a hydrometer.


$25 is pretty good! I'm about to make an order with reefcleaners, but can't find a refractometer anywhere on the site. Are you sure they sell them?

[j86miu]

$25 is pretty good! I'm about to make an order with reefcleaners, but can't find a refractometer anywhere on the site. Are you sure they sell them?

I cant find it either. The one I ordered from amazon is like 80 bucks :( I got it be because it had the best reviews and automatic temperature corrections. Are there really good cheap ones out there I can get instead?

[Palting]

Swing arm hydrometers are getting a bum rap for no good reason. I have 2 hydrometers and one refractometer. I bought the second swing arm because I accidently stepped on the first one and cracked it. Once in a while, just so I can feel "special", I calibrate my refractomer with the PinPoint reference fluid, then do readings of the water change water and the tank, and even the discard water. The swing arm and the refractometer read the same, even the cracked swing arm hydrometer!!

IMO, the only time you NEED a refractometer is when you do hyposalinity and have to go down to an SG of 1.009. Or maybe if you need to calibrate for temperature, like if you keep your tank at above 85F or below 65F, although I don't know when THAT temp would ever be a good idea :D. My tank temp varies a few degrees, and I use the swing arm for regular maintenance checks with no issues.

[benjc]

MarineDepot sells refractometers for 45ish; sometimes better deals can be had on Ebay. Just make sure you get one with auto temp. correction.