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View Full Version : Pinpoint Salt Monitor vs. Hydrometer


FSOL
12/15/2006, 11:54 AM
OK so I purchased a pinpoint salt monitor in hopes of not having to use my hydrometer every time.
Now I'm doing more work. The hydrometer reads a SG that's way off from the monitor.
For example hydrometer reads 1.030SG while monitor reads 1.025SG.

The hydrometer is brand new and the monitor is a few weeks old and been calibrated few days ago.
Why such a big difference? Should I rely more on the hydrometer or the pinpoint monitor?

Thanks

siding88
12/15/2006, 12:00 PM
i'll tag along on this one too,,,,,,,,i get a lower reading with the pinpoint also u would think for that cash i would be dead on

FSOL
12/15/2006, 12:09 PM
That's what I thought when I purchased it. The damn thing falls off of calibration fast, too. I calibrate it w/ the 53ms solution, use it for a few measurements in the tank, and clean the probe, put it back in the calibration solution, and now it reads 53.2 or 52.7.
Not sure if you have this same problem? I don't think it should fall off of calibration in a matter of a few measurements.

RobbyG
12/15/2006, 01:27 PM
Tagging along also, I always thought that Refractometers and Hydrometers were the most accurate but of late many people have been saying the Pinpoint is more accurate. Very confusing!

FlipFlops24/7
12/15/2006, 01:57 PM
Tagging along too. I almost ordered a Pinpoint Salinity monitor today, but am holding off. The Pinpoint PH monitor that I have is spot on. Im surprised to hear that the Salinity monitor has issues

FSOL
12/15/2006, 02:57 PM
Well this hobby is full of uncertainty and sometimes b.s. from forum members. I'm sure someone who works for American marine will come and say their pinpoint monitor always works dead on. I wish there was more certainty in this hobby :)

Anyways, hopefully someone can chime in and help us out. So far there's more questions than answers. I may contact American Marine and talk to them, see what they say.

loudell
12/15/2006, 04:08 PM
Generally speaking the PINPOINT Salinity Monitor is "dead on". Significant variables will be using a battery <preferred> instead of an AC Kit and perhaps a small amount of contamination/evaporation of the calibration fluid.
BTW FOSL if you are reading the salinity fluid as 53.2 whereas before you read it as 53.0 this is a specific gravity difference in approximately the 5th digit past the decimal. That is 1.026 before and 1.02603 on the second measurement. BTW the meter is probably correct for a minute amount of evaporation.

keeperofthefish
12/15/2006, 04:51 PM
Remember when you calibrate or take any readings to let the salinity meter sit in the solution for at least 3 minutes. Also stir it around a bit to ensure there are no air bubbles trapped. I just got mine last week and so far it seems pretty awesome. Definitely easier to use than the refractometer. Did you read the ReefKeeping article this month? It makes sense that you want to calibrate at the correct salinity for seawater. So far, I like it. Will let you know if I chance my mind. You're sure you didn't accidentally turn the wrong screw in calibrating it right? One of them will screw it up. And if it fluctuates too much, contact the manufacturer and demand a new one! Should work great.

IBASSFSH
12/15/2006, 08:23 PM
I love mine. I have only calibrated it once since I bought it two years ago or so. (should probably re-calibrate it). I do not compare with a plastic hydrometer. Basically because you can take two different plastic hydrometers and get different readings.
Calibrate it and use it faithfully. How do you know the plastic hrdrometer is reading correctly? There is no calibration fluid for those that I know of.

RobbyG
12/16/2006, 04:44 PM
Loudell, I had PM'd you back about the Nitrate meter, but heard nothing from you, did you receive the PM?

<a href=showthread.php?s=&postid=8760608#post8760608 target=_blank>Originally posted</a> by loudell
Generally speaking the PINPOINT Salinity Monitor is "dead on". Significant variables will be using a battery <preferred> instead of an AC Kit and perhaps a small amount of contamination/evaporation of the calibration fluid.
BTW FOSL if you are reading the salinity fluid as 53.2 whereas before you read it as 53.0 this is a specific gravity difference in approximately the 5th digit past the decimal. That is 1.026 before and 1.02603 on the second measurement. BTW the meter is probably correct for a minute amount of evaporation.

loudell
12/16/2006, 07:21 PM
PM'd you Robby....