Hydrometer question!!

[kalani]

Hey guys. I have a problem. I've been using a thermometer type of hydrometer and just bought a Instant Ocean hydrometer by marinelabs. The readings are totally off on both. Which one is more reliable? This thing driving me nuts. TIA

 

[bill0298]

When I first bought my swing arm hydrometer, my LFS told me I had to soak it in my salt water over night before I would get good readings. Once I did that and made sure there were no bubbles on the arm I didn't have any more problems. However, I have heard that the refractometers are more accruate and less trouble..

 

[darb2]

a hydrometer should be at least 12" and you need to turn off all pumps and ph to get an accurate reading. You may also have to compensate for temp because most of them are calibrated for 76 F. At 82 F the hydrometer should read at 1.024 to actually have 1.025 sg
Most swing arms read low
That is why I picked up a refractometer on ebay for like 30 bucks

 

[Sparky]

My bobber hydrometer I use came in a clear plastic case that is 18 long. I can fill that with the tank water and put the hydometer inside and get a nice reading. The only proble is like darb said, you will have to calculate the "exact" SG reading based on temp. I also use a refractometer. I have both the floating and swinf arm hydrometers also. Just in case. Mine seem to be pretty close in reading with each other.

Mike

 

[Atari]

I've had an Instant Ocean hydrometer and it was all but impossible to get an accurate reading after a few months, even after numerous soaks in vinegar. When it worked it read 1.024 when my refractometer read 1.022.

I second the recommendation for a refractometer.

 

[MantisFreak]

I like the accuracy of refractometers but obviously there is a substantial price difference. However, most people's refractometers are not as accurate as they think. Most refractometers are calibrated with pure sodium chloride and not NSW. As a result, you should add .015 or 1.5 ppt to all measurements from them unless you recalibrate it yourself. Your hydrometer was closer than you thought.

Also, you should read these articles by RHF
http://reefkeeping.com/issues/2004-07/rhf/index.htm
http://reefkeeping.com/issues/2004-06/rhf/index.htm

 

[Atari]

Yeah sorry, my point was that it was hard to get a consistent reading with the hydrometer. I remember doing a lot of tapping.

 

[phases99]

Hey guys. I have a problem. I've been using a thermometer type of hydrometer and just bought a Instant Ocean hydrometer by marinelabs. The readings are totally off on both. Which one is more reliable? This thing driving me nuts. TIA

I had the same problem when I started my tank. I bought a 12" glass hydrometer from Hagen and used it to get things going. After I dropped it on the floor and broke it into a million pieces I bought an plastic box one which told me my water was 1.029. I went to the LFS and calibrated against theirs and found that the plastic one was almost right on. I had to slowly bring my tank from 1.029 to 1.025 over a couple of days. Luckily I had no fish yet but I might have done some damage to my LR.

 

[PatM]

I also have the Instant Ocean hydrometer and just noticed today some rather unusual readings after 8 months of accurate service. I am going to see what the lfs tests my water at but I think the refractometer is the more accurate way to go.

 

[XXFirefighter]

I soaked the my IO in my tank water for 3 days and then i was fine. No problems !

 

[PatM]

Maybe I will try to soak mine and see if it reads right again.

 

[MantisFreak]

You can add a little vinegar to the RO/DI water and that helps clean them better. Good Luck!

 

[fishman]

Along the same line, someone mentioned that refrac's are not as accurate as you think? Why is that? I dont see how it couldnt be more accurate than a swing arm..I would think it would be a lot closer to a true reading than a swing arm wouldnt it?