refractometer or pinpoint salinity monitor

[scooterr]

Which of these two is more accurate? They both retail for about 115 bucks. I have multiple tanks so the refractometer would have an advantage there. Which one would you recomend?
TIA
jeff

 

[golfish]

The refacrometer will be more accurate

 

[randy holmes-farley]

I'd go for the conductivity meter. In general, they are more accurate and precise than refractometers (though I've not specifically tested the pinpoint and expect that it is poorer than high quality units, just as hobby refractometers are not as accurate as high quality lab devices).

For hobby use, both are perfectly suitable, but conductivity is easier to use, IMO.

 

[botp2k1]

Jeff, the refractometer will be more accurate. Try this link, I do not know if the sale is in progress or begins in Oct, but the price is $70.
http://www.northcoastmarines.com/octsav.htm

 

[jdeets]

http://www.northcoastmarines.com

They have refractometers for $70. That's what I use. Great piece of equipment. When I bring home new livestock, I just take a few drops of water out of the plastic bag to check the salinity and compare it to the salinity of my system. When I take water samples into the kitchen to run tests, I can also check salinity with a couple of drops of water as well. BTW, the North Coast Marines refractometer automatically adjusts for temperature variations.

I'd recommend the refractometer. It's more portable, should be every bit as accurate as the meter, and I don't really see the point in constantly monitoring salinity. JMO

 

[randy holmes-farley]

Do you people claiming that refractometers are more accurate than conductivity meters have any evidence to support your claims? IMO, this is nonsense spread by people who hawk refractometers.

In the text "Chemical Oceonography" by Frank Millero, he shows conductivity meters to be more accurate than refractometers and a variety of other ways of measuring salinity (e.g., hydrometers, etc.). Oceonographers no longer use refractometers. Chemistry labs no longer use refractometers. They use conductivity probes.

I agree that both are more than accurate for hobbyists, but find the claims that refractometers are better to be rather untrue.

 

[botp2k1]

Randy, after I posted, I realized I used the wrong word. I actually meant to say the refractometer is in my opinion, more convenient to use and maintain. I do not want to deceive anyone into one is better than the other. As I have found over the years, how well a piece of equipment functions depends a lot on the operator.

 

[golfish]

I don't think Randy read the whole post. Jeff wants to use this on more then one tank. Sure the conductivity meter is going to be a little more accurated but its going to be a pain to move from tank to tank unless its a hand held dohicky. The refractometer is more durable by far then a cheapo comductivity meter.

 

[Diablo]

I think that Randy DID read the post...

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote

Which of these two is more accurate?

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote

The refacrometer will be more accurate

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote

Jeff, the refractometer will be more accurate.

botp2k1 has since retracted his statement.

Randy was only responding to the above misinformation.

As for being suitable for multiple tanks, the Pinpoint is a hand held, battery operated unit:

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote

The refractometer is more durable by far then a cheapo comductivity meter.

First of all, if the refractometer costs the same as the pinpoint conductivity probe, then it too is a cheapo refractometer... I have seen high quality ones upward of $1000... thats not to say that the cheaper one is not adequate for aquarium use.

Also, seeing as you're making an unassailable statement of fact re: durability, I'd be very interested in your proof.

 

[Len]

I have very inadequete knowledge about scientific equipment, so here's my question:

Seeing that there are a lot of different free ions present (minerals, metals, dissolved gases) in our test solution (tank water), how does either instrument function to assure that the reading we're getting is a close approximation to actual salinity level (dry mass of NaCl per solution)? In other words, how do they negate the effects of other ions?

I would think how each accomplishes this would give insight as to which is more accurate.

And one important point to make: let's compare apples to apples (eg northcoast marine's refractometer to Pinpoint's conductivity meter). A $70 refractometer can not be compared to a $650 "poor man's" handheld refractometer, let alone a $5,000 lab TDS/conductivity/salinty device.

Thanks for the help.

 

[golfish]

Well, I guess I'll have to step up and say that I work in a LAB and we use Refractometers and conductivity meters along with all kinds of other BS meter. I don't ever remember someone coming in to a fix a refactometer. The 5000.00 meters go out all the time.

Diablo, I wasn't flaming Randy I just thought he missed the part about multiple tanks. When I compare the two meters the refractometer will outlast 5 conductivity meters easy. That's why I would "recomend" the Refractometer.

I too have seen high quality refractometer and they compare to the 70.00 units. I don't recall ever seeing a 1000.00 hand held refractometer.

[ September 25, 2001: Message edited by: golfish ]

[ September 25, 2001: Message edited by: golfish ]

 

[scooterr]

Thanks for all the coments. I think I will go with the refractometer from North coast marines. Since it seems that both are adequate i will get the cheaper one.
jeff

 

[golfish]

Your right, I should not have said "The refacrometer will be more accurate" I should have said the refractometer will be a better choice.

 

[polyp]

I've got a conductivity probe on my Aquacontroller, thus the probe is always in my sump... I need to have the temp probe in there as ground reference as well. I'm thinking of purchasing a refractometer (actually, the one mentioned above)as a useful "sanity check" to be certain I haven't mis-calibrated the conductivity meter reading, and to double check against calibration drift.

 

[suckair]

I have both. The refractomoter is more accurate! Hands down! I don't even pay much attention to the readings on the computer anymore.

Randall

 

[Baalz]

I have both the Pinpoint Salinity meter and the Northcoast Refractometer.
i lost severl acros due to the pinpoint. It seems it drifted from its settings. I am much happier using the refractometer.
Even now they both read vastly different.

 

[radium]

Personally, I just aim for a stable salinity rather than the numerically perfect salinity. My quirky pinpoint is good enough for that. I just fill it up, pour it out, and fill it back up (helps get rid of bubbles) and if the needle is where it was the day before I am fine.

If I had the cash to spend though, sure a refractometer would be a cool toy.

 

[AFH]

Hello All, I taught I would chime in on this one, I have owned both salinity monitor and a refractometer. They both work. Here is something to think about. If your salinity monitor gets wet will it work afterwards? My pinpoint does not. Refractometer no electrical parts safer around water.

 

[esmithiii]

I too have both, and will comment. Everything that I have read says that the salinity monitor is more accurate as well as precise. The conductivity meter is BY FAR MUCH MORE CONVENIENT AND EASY TO USE. Let me be clear: the refractometer is MORE DIFFICULT! The probe you simply place in your tank, wait 20 seconds and read. The refractometer you have to place drops of tank water on the glass, make sure there are no bubbles, wait 30 seconds, look through the glass into the light, make the reading, clean the glass and the plastic cover, clean the pipette or eye dropper, replace the unit in its case and place the case in a cool dry place.

To use the salinity monitor in multiple tanks is very easy. The probe of the monitor from PinPoint was not designed to be placed continually in the tank.

The only issue I have had from the pinpoint monitor was that after a year of use, it started acting strangely. I bought the refractometer as a backup, but hope to get the monitor working again because the refractometer is such a pain in the butt.

E

 

[esmithiii]

AFH:

Read the booklet that came with your refractometer:

"The optics in your refractometer will be damaged if the unit is submerged or if fluids come into contact with any part other than the sample plate"