Two hydrometer...Two different readings

[option720]

Hey here is a quick question for you all. My brother in law just bought Sea Test hydrometer and was testing it's readings versus my Coral Life Deep Six. Mine reads 1.022 and his read 1.026. What is the deal? the coral life is about one year old, can they go bad. Need some help here.
Thanks in advance
Emile

 

[beth]

I found the same thing to be the case when I tried comparing these 2 hydrometers. I found, then, that the deep 6 matched up with a standard floating hydrometer, so I went with the deep 6 as being most accurate.

 

[jimi]

The deal is hydrometers are simple inaccurate measuring devices. Thats why I bought an refractometer.

 

[aquarius]

Yeah I had the same thing happen with my two hydrometers. We originally used the plastic sea test one and when compared to a more advanced thermometer like one, the reading was way off. We bought two more sea tests just to see if it was the particular one but they were all off. So I'd chuck the Sea Test.

 

[aquaman2]

jimi how much was your refractometor

 

[fishfreek]

aquarius, i currently am using a Sea Test hydrometer. Are you using the glass tube type hydrometer that floats? If i'm not mistaken, these are about the same cost as the plastic type sea test hydrometers aren't they? Does anyone else know if the floating glass tube type are more reliable? I didn't realize that they are so inaccurate!
[ August 06, 2001: Message edited by: fishfreek ]

 

[glenn]

If you can ...check it with your LFS if they have the refactor one. That way you can tell if either is right. Also yes they can go bad. Agrain of salt in the wrong place or anything else for that matter will affect them.
Glenn

 

[fugu]

i had the same problem with the hydrometers. i only use a refractometer now. the only way to go. also be sure to clean your hydrometers thoroughly after each use if you stick to that method. goodluck.

 

[pufferlover]

One recommended way to clean the plastic ones is to put in some vinegar for a bit then rinse it very well that will remove any gunk inside of it. I have had my hydrometer measured by my lfs guy and found it off only one point against his expensive refractometer. In fact he had just bought one for the store and in testing all his swing arm gauges he had used the most one was off was 2 points. So they can't be all that bad in the end.

 

[jimi]

Aquaman2 I bought my refractometer on sale for $70 it works great. Pufferlover as fart as hydrometers being off a point or two most are off two or more both of mine were. that could be critical successful hyposalinity treatments or if someone happens to be happy with low salinity like 1.020 and really has 1.017 or lower and wonders why there inverts die.

 

[misty]

I just make sure that my incorrect Deep Six measurements are consistent!

 

[oceanblue]

are we sure they're off? most of the hydrometer's are calibrated for 60deg.F, so they appear to be off if your not doing the temperature conversion...I've read this in a number of books I have and seen it on some websites..oh just thought of one...FINS resource states this also, and gives you the temp. conversion chart as well. anywho let me know what you all think...laters

 

[pufferlover]

Oceanblue; You made the best point so far you are right in that they are set for various temps and that does effect there accuracy. Frankly I forgot all about that till you mentioned it and then remembered a chart I saw on their site for conversion to the various temps. In regards to being off based on a refractometer out of 6 the lfs had one was dead on, 4 were 1 point off, and one was 2 points off. Frankly one or two points except when doing Hypo would never bother me as I keep my tanks (except reef) at .1020 based on my gauge and one or two off still keeps them in excellent range anyway.

 

[fishfreek]

I have the Sea Test hydrometer. Can some one tell me (because i don't have a conversion chart) What the SG would be in 81 degree water? My SG usually reads about 1.024 in my 1 yr old hydrometer.
Thanks alot!

 

[misty]

I think the ideal SG for 80 degrees is 1.022. I can't find where I read that, but I put it into my memory as being "right".

 

[twoods71]

Degrees F. Correction
50 -0.0005
55 -0.0002
60 0.0000
65 0.0004
70 0.0010
75 0.0017
80 0.0024
85 0.0032
90 0.0040
Above is a correction table.
So you can see that a temp of 81 and a SG reading of 1.024 would actually be around 1.026 after the temp correction.
The above chart is for a hydrometer calibrated at 60F