Hydrometer vs. Refractometer Test

[wayne in norway]

If he gotten 12 hydrometers to calibrate by luck, that is more than 'real lucky'. I don't want to know the odds, but i would bet they're pretty high, even for a simple yes/no test. Is that 2 to raised to the power 12, 4096?
If it low, accurate, high... 1 in 531441....

 

[flyyyguy]

Same bet would go with you my riend on the .005 off EVERY time proven wrong in less then ten seconds ; )

Hydrometers SUCK. But i never said they didnt. : )

 

[RobbyG]

Interesting, mine is off by .005 also.
I just redid the scale settings on the side with a sharpy marker. It's a piece of crap but the swing arms are so simple in nature that they are a good backup if you think your refractomemer or electronic seesor are malfunctioning, and that is about only use I have found for my hydrometer

 

[flyyyguy]

To be sure..........when i say they wont be .05 off regularly, that has nothing to do with what is marked from the factory on the hydrometer.........i mean from the mark i make on it after calibrating it to my refractometer. The marks on the hydrometer mean nothing......


Just for conversation purposes i encouorage you to calibrate your hydrometer to your refractometer, and write new numbers on it.........THEN take measurements with your refractometer side by side and will not be that far off.

Silly conversation really, but i encourage any of you to do that little experiment and then tell me it is 5 points off every time.

When i am messing with cooking rock or soemthing not so crucial i just know that 1.030 on my hyydrometer is more like 1.026.....where i keep my tanks.

 

[RobbyG]

BTW somebody commented that you could not recalibrate a swing arm unit. That is not entirely true since most of them seem to read high, all you need to do is FILE away small pieces of plastic from the edge of the arm till you get the right reading.
This would take long but it would at least give you an accurate unit without rewritting the scale on the side.

 

[flyyyguy]

I could be wrong robbyg as i havent done it, but i would think that filing pieces off of it would take it the wrong direction and make it read even higher yet..........
Air bubbles and mineral buildup both affect the weight of the swing arm as well.
Moral of the story.......if you dont have a refractometer......BUY ONE. : )

 

[Fredfish]

I have used both swing arm and glass. I find that, if properly maintained, both of them give consistant results. For the plastic hydrometer, I always rinsed in RO water and once a week gave it a good soak in RO.

I did find my swing arm hydrometer was off considerably when I compared it against several others.

Fred

 

[RobbyG]

Hmmm I might be wrong I thought the swing arm was lighter than SW so that filing off a piece would remove some of it's buoyancy, less water displaced. Now I am confused.

<a href=showthread.php?s=&postid=8211051#post8211051 target=_blank>Originally posted</a> by flyyyguy
I could be wrong robbyg as i havent done it, but i would think that filing pieces off of it would take it the wrong direction and make it read even higher yet..........
Air bubbles and mineral buildup both affect the weight of the swing arm as well.
Moral of the story.......if you dont have a refractometer......BUY ONE. : )

 

[Cosmo^Kramer]

I've been using a Seatest swing arm by Aquarium systems for quite awhile.I got it back when Randys Homemade Calibration Standards article came out.It was dead on.I just mix up a batch of Calibration water and test it every few weeks.I do clean it RO/DI water after every use,I think thats why it's been working correctly for so long.

 

[poknsnok]

I used a swing arm before I got my refractor and the swing arm was way off. it was reading 1025 and the refractometer was reading 1028!! whoa!!... spend 40.00 and get a refractometer