Just a little FYI

[ricky1414]

Did some of the newer reefkeepers know that when your swing arm hydrometer reads 1.025, that is not your true specific gravity? I just learned that. Thought I would pass it on. Turns out that what I thought was 1.025 was actually 1.0271 at 78 degrees. Here is a link to adjust your specific gravity. http://www.aquasite.com/knowledge/calcu ... ator.shtml
BTW, is 1.0271 too high of a specific gravity for my tank? Thanks

 

[Len]

Yep, hydrometers are calibrated to display specific gravity at a given temperature. As the temp changes, the scale changes too.

I recommend refractometers. They're much more accurate.

1.027 isn't too high a S.G., but it is on the high side. For your reference, it's like the specific gravity of the Red Sea, and NSW is about 1.02518.

 

[M@]

All hydrometers are dependant on temperature, but most that are designed for aquariums are calibrated between 70 and 80 *F

 

[Anonymous]

im not too keen on the accuracy of hydrometers either...

 

[hdtran]

Admittedly, the swing-arm hydrometers are not nearly as accurate as advertised (+/- 0.001). On the other hand, the label on the box claims that they are accurate over the range 60 to 85F (or something like that). It's easy enough to design the swing-arm hydrometers to be temperature compensated (in fact, it's difficult to make them not temperature compensated) due to thermal expansion of the plastic.

Next time I make some saltwater, I'll try to remember to microwave some, and see if my cheap swing-arm model reads a different SG.

 

[Anonymous]

actually it should..i have one by seatest and boy does the change in water temp make a dif in the specific gravity...i try to get the water to be the same temp as my tank so its possibly a little more accurate...however i agree with Len and use a refractometer for better accuracy...i cant say that from personal experience however ive really never heard of too many negatives using a refractometer... my 2cents and a hay penny...

 

[knpjdad]

I think I'm going to throw all my swing-arm hydrometers away... Example.. From the same tank. First swing-arm reads 1.023, 2nd swing arm reads 1.027.. So then, in goes the floating glass hydrometer, and it reads 1.020? Wonder which one I should write down in my log book?

refractometer is looking better all the time!!

 

[Anonymous]

like you said..Refractometer...