Inaccurate Salinity

I'd recommend a conductivity meter. I have American Marine's Pinpoint Salinity Monitor, and it works great. You have to give the probe a minute or two to temperature compensate, but it's one of the easiest ways to measure salinity I've ever used. Drop the probe in your sample, walk away for a few minutes, come back, read the value. Rinse the probe in lukewarm water, and you're done. I used to calibrate mine every month, but the calibration was spot on every single time I measured it. So I stopped checking haha. Haven't checked in a year or so.

I'll look at them - I'm about to move to a continuous water change setup on at least 1 of my tanks - one thing that I'm a little stressed about with doing so is maintaining salinity across that tank and my water change setup.
 
I want it to work really bad. To the point that I have tried at least 1/2 dozen times to figure out what I'm doing wrong. I currently have 3 tanks plus mixing station and I would love a quick way to test all 4 in a short period of time.

No matter what I try I am unable to get reliable readings. I'm tempted to purchase another one to see if maybe I got a bad or mishandled one but I really don't want to throw another $135 down the drain.

And Milwaukees support was way less than stellar when I called to ask if they had any ideas on why I am unable to get accurate reproducible results. When I told the tech the calibration solution wouldn't even read at 1.000 +/- .002 after a calibration his response was "well why would anyone want to read the calibration solution, that's to calibrate with". I tried to explain I would think that whatever I just used to calibrate the device with should at least be read by the machine pretty darn close to the calibrated value.

For know I'm stuck with my handheld Red Sea refractometer which takes an extra minute or 2 but has never given a bad reading from what I can tell.
here is exactly how i use mine. I use the bottle of distilled water that it came with (filled it with rodi because i used it all). put that water on the prism and fully cover the lens with water using the distilled dropper only. Eliminate the chance for cross contamination with saltwater. Do not use the dropper for s.w. the distilled water, and the meter should both be room temp. Hit the zero button. It should read 1.000. I then just use my normal dropper and suck the distilled off of the prism, and spray it on the floor, on my pantleg, wherever. Next, i fill and empty my s.w dropper a few times with tank water, to flush it and get a good sample. I then fill, and empty the prism, to flush any remaining distilled off of it. I then refill the s.w dropper, and fill the prism with s.w to be tested, just enough to cover the lens opening. Let it temperature adjust for 30 secs, and hit read. There is your measurement. I usually wait another 10 secs or so, amd read again, so to see if it stays the same. Yoy can then get another sw sample, and test again, if you want. When im done, i bring the meter to the sink, run water over it to rinse off any salt, dry it gently with whatever towels around, and put it away. I used this same method, but with the included 1.025 cal solution, and it tested 1.025 dead on. And this goes for BOTH mine, and works meters. I am fully happy and confident in them. They have been very consistent. So either ( no offense, im sure you're not the problem) you're doing something wrong, or this meter was dropped at some point, or is faulty in some way. Im sorry about that crappy customer service. That is a shame, because i do think it is a good product, and they should stand behind it, and they should WANT you to be able to use it. Good luck.
 
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I appreciate you saying out how you are doing it - I'll keep messing with it and try again.

Your process is similar to what I have been doing - use distilled water, dedicated dropper, put water in well, wipe with paper towel, add more to well, wait at least 30 seconds, push calibrate. Soak up distilled water, fill / empty SW dropper several times, place SW sample on well, wait at least 30 seconds, push measure. Here comes the bad part - if I wait another 30 seconds, push measure again - I'll get a different reading. Not within margin of error, I'm talking a variance of .010 or more. Test again (without touching the SW that is in the well) and get yet another number. Dry the well out, place distilled water in well, dry, add distilled water again, push measure and I'll either get an error or some random measurement. Very rarely will that produce a measurement of 1.000 +/- .oo2 - which it should.

I seriously think I need to record my process and ask Milwaukee to tell me what they think is wrong.

I also wondered if ambient light had something to do with it - I'm able to replicate the above results even if I place my hand over the well to block most room light. Also tried replacing battery.

here is exactly how i use mine. I use the bottle of distilled water that it came with (filled it with rodi because i used it all). put that water on the prism and fully cover the lens with water using the distilled dropper only. Eliminate the chance for cross contamination with saltwater. Do not use the dropper for s.w. the distilled water, and the meter should both be room temp. Hit the zero button. It should read 1.000. I then just use my normal dropper and suck the distilled off of the prism, and spray it on the floor, on my pantleg, wherever. Next, i fill and empty my s.w dropper a few times with tank water, to flush it and get a good sample. I then fill, and empty the prism, to flush any remaining distilled off of it. I then refill the s.w dropper, and fill the prism with s.w to be tested, just enough to cover the lens opening. Let it temperature adjust for 30 secs, and hit read. There is your measurement. I usually wait another 10 secs or so, amd read again, so to see if it stays the same. Yoy can then get another sw sample, and test again, if you want. When im done, i bring the meter to the sink, run water over it to rinse off any salt, dry it gently with whatever towels around, and put it away. I used this same method, but with the included 1.025 cal solution, and it tested 1.025 dead on. And this goes for BOTH mine, and works meters. I am fully happy and confident in them. They have been very consistent. So either ( no offense, im sure you're not the problem) you're doing something wrong, or this meter was dropped at some point, or is faulty in some way. Im sorry about that crappy customer service. That is a shame, because i do think it is a good product, and they should stand behind it, and they should WANT you to be able to use it. Good luck.
Also, in the directions, it says if you are in bright light, to shade the prism with your hand, before reading.
 
I appreciate you saying out how you are doing it - I'll keep messing with it and try again.

Your process is similar to what I have been doing - use distilled water, dedicated dropper, put water in well, wipe with paper towel, add more to well, wait at least 30 seconds, push calibrate. Soak up distilled water, fill / empty SW dropper several times, place SW sample on well, wait at least 30 seconds, push measure. Here comes the bad part - if I wait another 30 seconds, push measure again - I'll get a different reading. Not within margin of error, I'm talking a variance of .010 or more. Test again (without touching the SW that is in the well) and get yet another number. Dry the well out, place distilled water in well, dry, add distilled water again, push measure and I'll either get an error or some random measurement. Very rarely will that produce a measurement of 1.000 +/- .oo2 - which it should.

I seriously think I need to record my process and ask Milwaukee to tell me what they think is wrong.

I also wondered if ambient light had something to do with it - I'm able to replicate the above results even if I place my hand over the well to block most room light. Also tried replacing battery.
i doubt its a light problem. Ive never had mine measure differently whether i block ambient light or not. I think that is really only relevant in direct sunlight.
 
The Milwaukee units are pretty reliable in my estimation. I know a lot of people using these units with thriving reef tanks. This thread inspired me to test my recently retired Milwaukee unit against a more precise (if you believe the marketing material) and expensive (it was a painful purchase) Misco refractometer and had nearly identical readings. I used the same distilled water to zero each unit and fresh BRS calibration/reference solution in both units for the final measurement and conducted the test twice.

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IF YOU HAD TO TAKE A REEFING EXAM, WOULD YOU PASS?

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