A lesson learned and a warning too!!

[lubeck]

i believe your right however needless to say your hydrometer was inaccurate... i believe it was 200 parts per thousand off which if you tried to correct it from 1.022 to 1.024 your really, according to the refractometer to 1.026 which infact is a great sg for a reef tank however jumping 400ppt would be deadly/stressfull to your tank.
i am glad you got a refractometer the same thing happened to me a year ago the hydromter showing 1.025 but after getting the refractometer showing 1.022.

 

[djmx2002]

i guess they just wear out... without reading this tread i wouldn't even noticed it, when i first got the refrectometer it showed me the same reading as my hydrometer so i just thought it would be easier to user the hydrometer, now couple of months after it does shows a 'slight' shift.
and i agree with you if i would try to change it at the moment it would be deadly to my inhabitits of the tank,
however when everything seems healthy i didn't think about trying to fix it to be honest.... lol
i think i will start using the refrectomer more often now

 

[tx reef]

My glass floating hydrometer has never been off. It has been checked against refractometers several times and has always been dead on. Remember, if you are going to use a hydrometer, read up on adjustments you need to make for temperature.

 

[dragonboy]

I heard the glass floating hydrometer are pretty accurate since their the oldest ones around.

 

[darknes]

I think people mix things up between salinity and specific gravity. You cannot say that your refractometer shows 1.024 and your hydrometer shows 1.022, and say that they don't match up.
A hydrometer measures specific gravity, whereas a refractometer measures salinity. You should never say your salt level is 1.025 or whatever without giving a temperature. Your specific gravity could be 1.025, but the salinity could still be way off if the temperature is different than what your hyrometer reads. Therefore, it's best to say your salt level in terms of ppt (parts per thousand), and if using a hydrometer you have to convert your specific gravity to ppt using a chart.
Here's an archived thread that explains things well:
https://www.saltwaterfish.com/vb/showthread.php?t=49255

 

[candycane]

Originally Posted by djmx2002
i guess they just wear out... without reading this tread i wouldn't even noticed it, when i first got the refrectometer it showed me the same reading as my hydrometer so i just thought it would be easier to user the hydrometer, now couple of months after it does shows a 'slight' shift.
and i agree with you if i would try to change it at the moment it would be deadly to my inhabitits of the tank,
however when everything seems healthy i didn't think about trying to fix it to be honest.... lol
i think i will start using the refrectomer more often now
I don't get why people don't look at the beginning of the story and they just cut right to the end. Not saying that is bad. Is there something horribly wrong with your fish? Is everything curling up and dying or burning? If it aint broke............

 

[candycane]

Originally Posted by dragonboy
I heard the glass floating hydrometer are pretty accurate since their the oldest ones around.
LOL! Those were the ones that I was talking about when i was talking about the ones that you just lob across the room and hope they land in your tank. They look like GIANT thermometers. But they just float around your tank and you try to catch a reading when the powerhead blows it by.

 

[sonnyg]

i took my floating hydrometer and tossed it from across the room, now i have little lead balls all over the bottom of my tank. (just kidding) i use the plastic cheapo type. we have 5 in the house, i just keep using the same one. hell if its wrong my corals and fish dont care. and if we are so worried about this . ever wonder if all the drops you use testing everything else are the same size? think of it testing dkh and having oversize drops going into the test tube? two drops reading like three might throw you off .6 dkh

 

[1journeyman]

Originally Posted by Darknes
A hydrometer measures specific gravity, whereas a refractometer measures salinity.
I think Refracts measure both, one on each side. I know mine does.

 

[bang guy]

Originally Posted by 1journeyman
I think Refracts measure both, one on each side. I know mine does.
The S.G. scale on a refractometer is only accurate at a single specific temperature.
Refractometers use light refraction to calculate Salinity. They cannot measure water density.
Hydrometers measure Water Density they cannot measure salinity. To obtain the salinity you must know the temperature of the water and use a chart.

 

[1journeyman]

Well there ya go...