Newbie to Newbie: Refractometers

[iflyprops]

Okay, I just bought a middle of the line refractometer today. Before this I was using a swing arm hydrometer, I knew they were innacurate, but I didn't realize how bad. I just got home and checked my salinity, 1.029! My "deep six" swing arm was reading 1.025. Needless to say it will be "deep sixed." Moral of the story, and to agree with the experts on this forum: Buy a refractometer to begin with and take that ten bucks you would have spent on a swing arm and buy a fish, instead of basically throwing it away.

I'll chock this up to experience.
-Adam

 

[Desert Aquarium]

What price range are you talking about, on your middle of the line unit?

 

[mhhauser]

What is a Refractometer?
Whats a swing arm hydrometer?

I know they measure salinity.

 

[iflyprops]

This is a refractometer. It measures the different wavelengths of light coming through the water (correct me if I'm wrong). They have them on Dr. Fosters for $40. I paid $75 for a different model through my LFS.

This is a swing arm hydrometer. Very innacurate, as I found out. Save your money.


-Adam

 

[zukihara]

I found those swing arms have a nasty habit of being sticky which totally throws off any type of accuracy after a few uses (if it was indeed accurate from the beginning).

 

[tonytiger05]

the trick with the hydrometer is that you have to flick all the bubbles off the needle

 

[Paintbug]

you can get a good refractometer off ebay for $35 shipped now days. well worth it!! i bought 2 swing arms from the LFS that ended up costing me about $25. neither was close to accurate. they are consistant though. if you rinse them right after each use you will get consistant reading. so if you go the LFS and get them to check your swing arm to their refractometer, then you know how off it is you can still get accurate readings. but save the hasles and buy a refractometer

 

[JimR]

What about the one's that look like a thermometer in a glass tube, are they acurate?

The 3 in the above picture, are those battery operated? LCD read out? Do they have to be calibrated once in awhile ( I see the screw driver )? Is there any part that needs regular replacement?

 

[MOX]

no jim how they work is a drop or 2 of water is placed over the end a gate drops over compresing the water to be even then u look through it at a light source from what i here any light is fine and ull get ur read out i dont think their are any peices that would need replace unless broken but i am shure it needs calibrated but how i am also not shure

 

[Myrphie]

<a href=showthread.php?s=&postid=6531025#post6531025 target=_blank>Originally posted</a> by JimR
What about the one's that look like a thermometer in a glass tube, are they acurate?

The 3 in the above picture, are those battery operated? LCD read out? Do they have to be calibrated once in awhile ( I see the screw driver )? Is there any part that needs regular replacement?

Floating glass hydrometers need to be in still water to get an accurate reading as any current will make them bob in the water and potentially damage them.

As for the refractometers, there's nothing electronic about them, they are essentially prisms. You put a few drops of water on the lens and hold it up to your eye to take a reading. They do need to be calibrated occasionally but that's no more than taking pure water (DI or Distilled) and taking a baseline reading to make sure it's reading 1.0 and you adjust it with a small screw, typically.

Hope this helps!

 

[Paintbug]

the glass ones are about like the swing arms. of the 3 pictured i dont think any are battery operated. if you do see one thats battery operated, its generally just lighted so you dont have to find a good light source. you need to check any refractometer once in awhile to make sure its calibrated. there arent any parts to wear out though. they do make LCD monitors/controllers, they are in the $250 price range +/-

 

[jgoodrich71]

A good quality glass hydrometer will be more acurate than even a refractometer. The problem is that you have to fill a column with water and stick the hydrometer in the column of water. But these cost more than refractometer, and refractometer are so easy to use that it makes sense just to use a refractometer.

(We need to find some kind of short way to say refractometer. I just spelled out refractometer 5 ... no 6 times)

 

[JimR]

ok, thanx.