Hydrometer readings change with age

CDaubs

CDaubs

Reefing newb
I read somewhere on here that older hydrometers will give false readings after a couple of years. I was out shopping the other day and decided I would get a new hydrometer just in case.

When I got home I tested my water and sure enough the old one read that my water was right on. The new one showed my salinity was too high! :grumble:

After a partial water change I'm back on track. Who knew? I sure didn't.

This web site is great! :bowdown:
 
Hydrometers can vary drastically from one to another. Many people on this site prefer refractometers. They are more accurate and will last a lot longer. You can get one off of ebay for less than 20 bucks, or from a fish supply web site for around 40.
 
Hydrometers should be replaced every 6 months. There have been tests done on their accuracy, and even new ones can be very off of the actual reading.

Given the costs of replacing hydrometers periodically, it does pay off to just get a refractometer, as BJ pointedo out. Plus, refractometers are much more fun to use! :)
 
Hydrometers can vary evidently. Mine is 12 years and still works great! I got scared awhile back, with all the talk on here about bad hydrometers. So I went and ordered a refractometer . When i compared the two, they were identical. So i guess its all in the one you own.
 
If you have a hydrometer that floats in a container to read salinity, it's probably pretty accurate. If you have a swing arm hydrometer (where you fill a container with water and watch the arm move to the salinity reading), it's likely to be inaccurate sooner or later. Go refractometer. I got a used one from my LFS for $25. Also note that most modern refractometers automatically compensate for temperature differences, while neither style of hydrometer can do that.
 
Glass floating hydrometers are pretty accurate....i had one that was .002 off....
I now use a refractometer ....
 
Here's some proof for you. My LFS rarely have refractometers in stock, so I use hydrometers. I bought a new one a month or so ago, figured I'd test the accuracy. This is the old one next to the new one.
 

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wow. yeah, those hydrometers are a pain... caused my little tank to crash, way back in the beginning, due to their inaccuracy.
 
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