Thinking about a refractometer.

[GrampaDon]

Believe this>> I still use a 5yr old swingarm SG box. < seriously

I'm ready to pick up thishttp://www.bulkreefsupply.com/store/products/test-kits/refractometer/refractometer-for-reading-salinity-w-free-calibration-fluid.html They seem inexpensive enough.

I feel comfortable they work great ,but I just want to know....do they need to be calibrated very often or not.??
Should I just get extra calibration fluid now.?

Reason im asking is stupid, I need RO filters anyway + I almost always try to order enough to get free shipping.

 

[bongarone]

Yes, get the $8 bottle of calibration fluid.

The best way to use it isn't necessarily to calibrate the device, but rather use it as a comparator between the fluid and your tank water. If they match, your salinity is good.

 

[jagr200]

You can also use distilled water to calibrate. Thats what I use and that and my swing arm match.

 

[codeblue48]

I just use RO water to calibrate mine. Haven't needed to recalibrate it since.

 

[maynardjames]

for 8 bucks you can calibrate every time if u wanted.i would think it would last a year if you used everyday. most of the chem gurus here recommend using it. not sure how often

 

[wolfador]

I don't think you need the extra fluid. It comes with some and you only need a few drops to calibrate.

It does come with a big sticker on the box that says to not calibrate it using RO.

 

[yh1185]

Using RO water to calibrate a refractometer is not going to help very much. The reason to use the pre-determined sg solutions is because of what your reading from your refractometer. Since most reef tanks read around 1.025, having solutions that are near that value are going to insure your readings are calibrated correctly. By using RO water, your making sure that the readings at 0 are good, and not at 1.025. The closer you can calibrate to the actual sg of your tank water, the more accurate the calibrating will be. HTH

 

[pete33]

I purchased a bottle of the solution since I've always calibrated with rodi. With the solution I found I was off by .0001. So, if I run out of the solution, I would just use the rodi and calibrate that to 1.001 and should actually match.

 

[icecool217]

I am shocked as see that the swingarm hasn't disappointed you in any way.

I've always used RO water to calibrate mine. If you want to be on the safe side, grab the calibration solution. 3 drops at most, and should last for a long time. You probably need to calibrate it once a year or less.

 

[sirreal63]

Using RO water to calibrate a refractometer is not going to help very much. The reason to use the pre-determined sg solutions is because of what your reading from your refractometer. Since most reef tanks read around 1.025, having solutions that are near that value are going to insure your readings are calibrated correctly. By using RO water, your making sure that the readings at 0 are good, and not at 1.025. The closer you can calibrate to the actual sg of your tank water, the more accurate the calibrating will be. HTH

This...+1

 

[Randy Holmes-Farley]

In reality, it is worse to use RO water than you guys are stating.

Most refractometers will give incorrect readings for seawater when calibrated with pure fresh water. That is because they are designed for sodium chloride solutions (brines) and not seawater.

That is why it is best to use a 35 ppt seawater standard. Such a standard, if made for a refractometer, cannot go wrong for measuring seawater salinity, while fresh water standards can.

i discuss these issues here:

Refractometers and Salinity Measurement
http://reefkeeping.com/issues/2006-12/rhf/index.php

Reef Aquarium Salinity: Homemade Calibration Standards
http://reefkeeping.com/issues/2004-06/rhf/index.htm

 

[OregonReefer2]

I've had mine about 8 months now. I check it every couple months but haven't had to adjust it yet.

 

[Dr Colliebreath]

Get and use the calibration solution. Check it every couple of times you use the refractometer. Sometimes they stay calibrated for a long time and sometimes they go out for no apparent reason (changes in temp, being set down too hard, etc.). In particular, check the refractometer if your reading indicates your salinity has changed a couple of points.

 

[GrampaDon]

Well thanks for the straight answers ,and the links Randy.

I will get the extra bottle mainly because its under 10 bucks so why not.

I really was more interested in how often these devices need to be rechecked. Sounds about par with a 39$ device.[no to bad]
Just cant justify getting a 200$ checker thingy.

 

[reefermonsters]

Refractometers are awesome. I really don’t think you will regret it if you buy one. I agree with everyone else on the calibration fluid issue. Calibration is absolutely essential to refractometers- they only work as well as your calibration. Make sure you get the calibration solution specifically designed to mimic aquarium seawater. The book mine came with also stated that it is better to calibrate using salinity close to that your measuring- so anywhere near 30-35 ppt @ 1ATM/78-80 deg f would be best. If the solution does not take it into account, you can even seal your calibration solution and throw it in your tank for 15 minutes. It will equilibrate to your tank’s temperature and you don’t have to worry about temperature influencing solubility. =) If you get one don’t calibrate with RO/DI water. If you have optima water you could probably use that but I would stick with the calibration solution.