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View Full Version : Floating Hydrometer vs Plastic needle?

sharkbait993
10/19/2006, 06:22 PM
Just bought a floater because I heard the plastic needle type were innacurate. My floater says I have 1.020 and the plastic Instant Ocean one says I have 1.024!! Yikes which one do I believe! And yes I tapped the plastic one a made sure there were no bubbles on the arm.

Thanks!!
EdKruzel
10/19/2006, 06:29 PM
It seems that the plastic hydrometer is a bit off; unfortunately this is common.

I have a plastic one that is right on with my refractometer but had to take back several before I found this one.
The floating hydrometers are accurate but a pain to keep as they are long and break easily if bumped or dropped.

Foster's and Smith has good deals on refractometers and the only thing necessary is to calibrate before use.

Ed
bertoni
10/19/2006, 06:31 PM
http://www.reefkeeping.com/issues/2004-06/rhf/index.php

That article describes a method of calibrating the devices you have.
meco65
10/19/2006, 07:45 PM
Have you rinsed the plastic hydrometer with fresh water? I take mine and fill it with tap water and let it set for a min. or two than rinse again. If you don’t rinse it the salt will build up on the arm and it will not read right, but by rinsing it that will not happen.
drummereef
10/19/2006, 08:33 PM
The floater is probably more accurate than the swing arm. Fill a small container with tank water and float the hydrometer in the container. Should be more accurate and safe.
EdKruzel
10/19/2006, 08:35 PM
<a href=showthread.php?s=&postid=8376060#post8376060 target=_blank>Originally posted</a> by meco65
Have you rinsed the plastic hydrometer with fresh water? I take mine and fill it with tap water and let it set for a min. or two than rinse again. If you don’t rinse it the salt will build up on the arm and it will not read right, but by rinsing it that will not happen.

Very good point; all tank equipment should be rinsed in fresh water after use.

Ed
nightOwl
10/19/2006, 09:09 PM
If you have the money buy a refractometer. I recently purchased one and its accurate. I found out my swingarm was off also. My swingarm was saying 1.025 when I used the refractometer it read 1.030. I have spent the last few days bringing it down. If you are in a local marine society see if you all can do a group buy and that will lower the price some. Like some others have said though, its always good to give it a fresh water bath also.

Hope that helps,

Henry