swing arm hygrometer

[undawahta]

yah, I know I need a spectrofangledwhoseldosselating (sp?) hydrometer but until then ...

 

if my pos swing arm meter tells me that nsw's sg ( filtered @scripps aquarium and heated to 80 ) is 1.027, my intuition is to assume that its off by ~2-4 thousanths of a unit off, and calculate by that.

 

anyone elses thoughts? (besides get a real test)

[newreefers]

a hydrometer could be off anywhere from .002 to .009. if you don't have a refractometer, take a sample to the lfs for testing.

[onthefly]

When I lived in SD, I used to get my water from Scripps and do the exact smae thing. For 3 years, it always measured 1.024 on my Hydrometer. Regardless, I never had a problem with it. Just remember, don't get water after a storm or during a red tide.

[onthefly]

I found that my swing arm was WAY high one day. Then I realized that there were a billion (well maybe not a billion.....but alot) of tiny bubbles on the arm. Therefore, my intial reading was something really high, but after giving it a good "flick" with my finger, the reading was where I expected it to be. Try the flick!

[Aggie05]

Can't you just have your LFS test it and then you test it with your equipment and if it is off make a note of it and always make sure to count in the difference? Did that make sense?

[MrConclusion]

Going to the LFS for testing is not always convenient, and usually they just dunp your water into a swing arm anyway. Free water testing is usually worth what you pay. The important thing is, to make sure there are no bubbles or micro-bubbles on the arm, and no debris either.

 

At 80 degrees, the SEATEST (common) hydrometer reads within .0005 (that's HALF A POINT) of true specific gravity. That's close enough that you have better things to worry about.

 

I work with hydrometers for a living and I can tell you that 99% of the errors are in the person using the device, a "bad" hydrometer that isn't obviously defective or broken is a rare thing.

[MrConclusion]

Oh, I forgot to mention...

 

At the risk of belaboring the point, I own a few refractometers - I sell them in my shop so I have easy access. They are commonly used for measuring sugar content of grapes to determine harvest time at vinyards.

 

Therefore, I've been able to check the accuracy of my hydrometers. I almost never bother to use a refractometer for aquarium applications, because I haven't found it to be necessary.

 

Unless you already have all of the toys you want, I would advise you to save your money.

[technoshaman]

I use a swing arm and then a standard glass floating hydrometer in some water I removed from tank in a flask. I take 2 sets of readings on each and look for any great variations. The glass one seems more accurate the plastic one as mentioned before seems prone to problems with bubbles, debris etc.

[BonkinBen]

Hi All, Greetings From Australia. i'm just at the beginning of setting up a Reef setup in my 19 G tank. I'm trying to get the salt levels right, and i have a hydrometer that u put down about 6 inches, then it fills up and the swing needle gives the reading. But if i do it in different places in the tank, i get a different reading, some high, some low! Any Ideas? thanks for anyone's help

[Yup]

I agree with newreefers, I was also told they could be off that much (LFS). My LFS actually tested my hydrometer against their refractometer, and I was .002 ppm low. Most GOOD LFS with help you and test stuff like this. I also had them test PH,Nitrates,Nitrites,Ammonia, and alk. to make sure my test readings were correct. Come to find out, my nitrate test was reading low b/c I was not shaking enough. I would have all new equipment tested or should I say calibrated. It really takes no time at all when you bring a water sample. Just hit the LFS at a slow time, not a sat or sun afternoon.