Deep six vs. refractometer

[VolitanFF]

I cannot hardly believe this.. I have two of the Deep Six Hydrometers and a refractometer. if these things are really this far off I cannot beleive they are even allowed to sell the Deep six.

my Deep six says 1.021
my refractometer says 1.026

is this really true? my refractometer came calibrated and I checked it with 0 TDS RO/DI water and it said 0 on the refractometer.

[tashier]

That's the way those things go. Now that you do know how far off the deep six is it's probably accurate as long as you always add .005 to it.

[DevilBoy]

i believe it. mine was off .004

[Wiskey]

I beleive it, I had 2 Deep-6's one was off 0.005, the other 0.006.

Whiskey

[beach bum]

deep six looks cool, has a cool name, and is close enough to keep your fish alive --- so they sell them by the truckload. I am glad you kicked out the dinero for a refractometer though, money very well spent (obviously).

[crvz]

No surprise. I very much enjoy my refractometer!

[Dagrape]

Here's my thought on it....

Regardless what Deep 6 says....if everything in your tank is happy....don't change anything.

If things are not happy then make the adjustment.

[VolitanFF]

Originally Posted by Dagrape

Here's my thought on it....

Regardless what Deep 6 says....if everything in your tank is happy....don't change anything.

If things are not happy then make the adjustment.

Yeah.. I know what you are saying.. but thats misleading to think your SG is fine when actually its not.. my 55 gallon I had at 1.028 before i bought my refractometer.. I was thinking I had my SG at 1.023 and it actually was way to high.. now that I slowly brought it down to 1.026 I feel a lil better about it.. not sure if the inhabitants think much of it.. but it makes me happy knowing it is now close to where it should be.

[Dagrape]

Peace of mind is one of the most important things to have......FWIW I am just setting up my 90 and before I put anything living in it I will be buying a refractometer aswell. I may beleive that there is nothing wrong with consitently wrong.........but I also beleive consitently right is WAY better!

[Tim224DT]

I dont know what my deep 6 reads vs my refractometer maybe i should check.

[know-it-all]

the refractometer is the only way to go

the local reef club did that as a topic on month
with a prize for the refractomer out the most

[avalanche wolf]

Went and checked mine , was .006 off !!!! Glad i have my refractor now !

[reefermike1]

mine was out .005 also. seems like if theyre all about that much off, it seems like they could just change the scale on the deep sixs and they would be accurate. idk, still glad i bought my refractometer. i dont even mess with the deep 6 atall anymore.

[stang5_o2002]

wow.... I better get a refractometer. I've been using the same deep six for over a year

[boxfishpooalot]

Hi guys, swing arm hydrometers work on the principle of buoyancy. If a solution has a certain amount of ions in it like saltwater does it will give off a certain buoyancy or weight in it. That buoyancy is what gives the measure of "lift" allowing the arm to float. Many things cause the arm to read improperly. Like a small microbubble attached to the arm can increase its buoyancy. Or even somthing not noticed, for instance soaking the hydrometer in vinegar to dissolve calcium precipitate. Vinegar will change the density of the plastic as the plastic takes in vinegar. Vinegar is lower density than saltwater at 35ppt. Mostly hydrometers are inacurate because its temerature sensitive. All of them are factory calibrated to read at an exact temperature, anything off swings its reading, or changes its density giving false buoyancy. Swing arms are not automatic temperature compensated. Aquarists need to read it at the temperture that the manufactuer has made it to read in. A better hydromter is one not effected by vinegar and air bubbles so much. Its called the glass floating hydrometer.

Refractometers work on the principle of light diffraction. There is a mirror that refracts the light which reads on a see through card inside. The position of the light refracted shows a diffraction line and is what gives a reading. Different density gives a different refractive index. They are also sensitive to temperature, as it is important to have an automatic temperature compensated refractometer. Bubbles also effect the available light diffusing through the sample plate reading inaccurate.