Milwaukee Seawater Refractometer MA887

[jason2459]

I ran across an LFS that was using one of these. They don't sell them but they let me check it out while I was there. It was really easy and super quick to use. They showed me calibrating it with RO/DI water to 0 and then testing it with PinPoint 53mS standard (again not something they sell!) Spot on to 35ppt three times in a row. I was excited. Wish they did sell both but they of course market to the masses and sell the standard hydrometers.

So, ordered one off of BRS's site and just got it in today. I was wanting one for two different areas I use them the most. It was either this or another refractometer. I drop on some 53mS Pinpoint solution and comes right up with 35ppt! Perfect. I drop on some from my tank and comes up as 37ppt. I drop some calibration fluid on my refractometer and looks like 35ppt to me. I drop on some from my tank on my refractometer and looks maybe slightly higher then 35ppt but certainly not 37ppt. I go to my other tank and exact same results. I have a vital sign from DFS and thought I've been keeping my tank at 35ppt. So, either my eyes suck, I'm not reading the line right, or the Milwaukee is off?

I've always read right where I see the line change color but not necessarily where it's the darkest. Have I been doing this wrong. Every Picture I see online on how to read a refractometer always has a super definite line but I always have seen a color gradient from light to dark and I always start right where I see it change. Should I be trying to decipher where it's the darkest point is? It's crazy but I feel like I trust the Milwaukee more as it keeps coming up with 35ppt and I've done it at least 10 times now with the Pinpoint solution.

Edit: Or, is my refractometer defective. Should there be a definitive line?

 

[jason2459]

Interesting results there. I've always used a light bulb that I go under. I've never tried reading it outside or by the light coming in from a window.

 

[jason2459]

I'll have to try it out this weekend as I normally get a chance to do most of my testing in the evening and the sun is going down a lot sooner now.

I guess I should have titled the thread what the heck am I doing wrong.

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[Boomer]

First, that is not a Milwaukee Seawater Refractometer but the Hanna modle HI 96822 renamed by Milwaukee. Hanna claims it is for seawater but they do not give any data used, like the RI of seawater @20 C 35 ppt.


HANNA Instruments HI 96822 Digital Refractometer, Salinity, Sea Water
http://www.eseasongear.com/hainhi96dire6.html


The F & Smith Vital Sine is a re-named Vee-Gee, model STX-3 Salinity Scale Optical Refractometer.
http://veegee.thomasnet.com/Asset/VEE-GEE-STX-3-Brochure.pdf

Here you can see how it reads 40 ppt

Either of these if calibrated in RO/DI water should read ~35 ppt z(see below) with PinPoint 53 mS.


Now we need to get into accuracy, NOT the number or line you see.

Hanna/Milwaukee +/- 2 ppt of reading

F & S Vital Sine +/- 1 ppt reading.

So, lets pretend that 53mS is eactly 53mS + 35 ppt and not 52.8 mS or 34.9 ppt.

They both show 35, fine. But one shows 35 and the other shows 36 but we know they should be exactly the same. So, why not ? Look at that accuracy

The Vee-Gee @ 35 ppt is somewhere between 34 ppt - 36 ppt and the Milwaukee @ 35 ppt is somewhere between 33 - 37 ppt. So, the Vee-Gee cold read 34 ppt and the Milwaukee could read 37 ppt but we know they should read 35 ppt as that is what the cal solution is if it is perfect 35 ppt / 53mS. Now, if if your 53mS Pinpoint is of and is really 34 ppt or 36 ppt.So, how do we solve this issue. Having a certified cal solution that is 35 ppt or 53mS. The PinPoint is not certified or guaranteed to be that but stuff form Sea Water Solutions is and cost an arm and leg. So, in a nut shell both of them are with in their guaranteed accuracy. Only getting a cal from like Sea Water Solutions will tell you which one is the accurate one.


Sea Water Solutions
http://www.seawatersolutions.com/

I would try this re-cal both in RO/DI water that has 0-1 ppm TDS and then test your tank to see what the two read.

Lastly you statement is confusing


I drop on some 53mS Pinpoint solution and comes right up with 35ppt!

Drop some on what the Vital or Milwaukee ?

I drop on some from my tank and comes up as 37ppt.

Drop some on what the Vital or Milwaukee ?

I drop some calibration fluid on my refractometer and looks like 35ppt to me.

Same

I drop on some from my tank on my refractometer and looks maybe slightly higher then 35ppt but certainly not 37ppt.

Same

I go to my other tank and exact same results. I have a vital sign from DFS and thought I've been keeping my tank at 35ppt. So, either my eyes suck, I'm not reading the line right, or the Milwaukee is off?

Same

Calibrated in RO/DI

Salinity..........53Ms......Tank......other tank

Mik ................??.?.........??.?...........??.?

Vital................??.?.........??.?...........??.?

Now, if you re-cal them both in 53 Ms they should be about the same 35 ppt

 

[jason2459]

What I see through my refractometer doesn't look anywhere close to that nice cut off line in that picture. There's always this gradient of really light blue to the dark blue. Hard to explain. Its not a real wide gradient and is about 1-2ppt in width.

I've always calibrated with the PinPoint solution but will Calibrate tonight with RO/DI water with 0 TDS and give that a go.

I use the PinPoint 53mS solution on the Milwaukee and consistently 100% of the time has come up as 35ppt. I've done a couple dozen times now. When I put water from either of my tanks on the Mik. it was coming up as 37ppt. I did that several times as well.

Using the vital-sine refractometer that I calibrated with the PinPoint solution to what I believe I see as 35ppt and adding tank water to it I see it as slightly higher then the 35ppt but not above 36ppt. Hard to read that small of a difference but there is a slightly higher difference from the PinPoint Solution.


Salinity..........53Ms......Tank......other tank

Mik ................35.........37...........37

Vital................35?.........35.5?...........35.5?


I hope that clarifies. I'm thinking I may just have a defective refractometer if there is suppose to be a definitive line like in the pictures. Could have been a drop? It's been like that ever since I got it over a year ago.

 

[jason2459]

I calibrated to zero on the refractometer. Interesting thing is the color gradient was almost none existent at 0. What I mean by that is there was a definite cut off to a blue but then it got dark blue and then back to the normal blue. I think something is wrong with my refractometer. I used right were I saw the color change to calibrate to.

I measured the pinpoint calibration solution with the refractometer and it looked exactly like it always does with the color gradients but 35 was slightly above where the color changes but not quite half way there.

I put the pinpoint solution on the Mik. and came right up with 35ppt.

I then went to my tank and placed some tank water on the refractometer and it looked slightly lower then 35ppt from where the color starts changing.

Put the tank water on the Mik. and it read 36ppt. Last night I took a little tank water out and this morning as well to let the ATO put in some fresh water a little at a time so both refractometer and Mik. show the decrease.

I just don't know where I should be reading the gradient and if I don't do it right where the color changes then I don't feel I can reliably tell where it hits the final color.

Boomer or anyone else that might have the vitalsign/veegee refractometer do I have a defective unit? I really wish I questioned the color gradient before as I'm not sure what the warranty is on these. I just thought the pictures were just pictures and a gradient might be normal and as long as I used right where the color changes I'm doing ok. I still don't know why it's not if using the same line each time.

 

[jason2459]

Didn't see warranty info for the vitalsign but I'm sure it's probably a year as that looks to be the warranty period for the veegee.

 

[Boomer]

Based on your numbers the Vital Sine is correct not the Milwaukee. The Vital is off 0.5 ppt and that Milwaukee is off 2.00 ppt.

Salinity..........53Ms......Tank......other tank

Mik ................35.........37...........37 35 - 37 = -2.00 ppt

Vital................35?.......35.5?.....35.5? 35 - 35 0.5 ppt= -0.5 ppt

Now as I tried to explain above the Vital is with in its +/- 1 ppt, mater of fact it is better than that at +/- 0.5 ppt. The Milwaukee is +/- 2 ppt and you are at the max of + 2 ppt. So, both meters are with in their accuracy guarantee. For example, that 37 ppt on the Milwaukee may really be 35.5 or 36 and not really 37.


How do you figure the Vital is defective ? If it is one of them it looks like the Milwaukee. JUST because the Milwaulee has digital numbers DOES NOT make it more correct, that is a myth. The guarantee of the Vial is 2.8 % and that on the Vital is 5.7 %. 2.8 % is better than 5.7 % by 2 x %

If you call either of these places and ask for an exchange they will tell no, as your meters are with its accuracy guarantee.

 

[Boomer]

I measured the pinpoint calibration solution with the refractometer and it looked exactly like it always does with the color gradients but 35 was slightly above where the color changes but not quite half way there.

Do you re-cal the Vital with the 53 mS so it reads 35ppt with the 53 mS on it ?

 

[jason2459]

I agree about the accuracy thing and digital does not = accuracy. What throws me off is with the Pinpoint 53mS solution the Milwaukee reeds 35ppt every time.

I'm also second guessing myself now with the color gradient on if I'm really reading it accurately and if it should be like that or not.


BTW, after calibrating to 0 I didn't calibrate again to 35ppt with the PinPoint solution.

 

[jason2459]

Well, here's an interesting update. Ordered the new D-D H2Ocean seawater refractometer and got it in today. First thing, SO much easier to read even fairly easy to see 1/2 increments of ppt. There is a definite cut to blue. Calibrated to 0 with RO/DI then referenced with three different Pinpoint 35ppt solutions and after leaving it sit for temp compensate it lined right up to 35ppt each time.

Got the Milwaukee out and calibrated to 0 with RO/DI as well. Then checked with the the same three 35ppt solutions and came right up with 35ppt.


Did the same with the Vitalsign and when using the 35ppt solution it looks at around 35ppt but not sure now as there is nothing like a clear cut to blue.

Tank water came up as 36ppt on the Mik., a clear 35.5 with the D-D, and what looks like 35ppt.

After seeing the picture as referenced by Boomer above and using D-D refract I believe my vitalsign is slightly damaged. Using a judgment call in calibration and testing gets it close enough. I believe the Mik is consistent but certainly not as accurate as a good Refractometer like my vitalsign/veegee could be if in good shape and the D-D I just got is.

Thanks Boomer for all your input.

 

[Boomer]

OK Jason.

I helped and gave the boys at D-D all the info for that new refract In the near future there will be updated model where the scale will be full and not cut-off look yours, which will make it even better. There will also be some adjustment needed on the focus tube , which now you have to unscrew it all the way out to get a clear image. We are only about 75 % happy with the way it is now. One thing on your Vital Sine vs the D-D. The Vital-Sine is a much sharper, brighter and easier to read screen in clarity than the D-D. Are you seeing this. Forget about the line distinction on this. If you do not see a better clarity of the numbers and lines on the scale window you may have a damaged one. Meaning, in the same light the D-D is harder to read the scale, lines and numbers printed on it. This is partly due to the way the D-D scale is colored and having to move the focus tube all the way out, which means less incoming light.

 

[jason2459]

I don't mind the scale being cut off at all. I wont be doing hyposalinity at all so it doesn't impact me. The scale and everything is much clearer and slightly brighter in the D-D compared to the vitalsign. Very happy with it. Edit: I really like the half increments are on the left and full on the right. Makes it easier to read the 1/2s.


BTW, I'm also not having to adjust the focus tube all the way out on the D-D, maybe 3/4 of the way.

 

[Boomer]

OK then there must be an issue with that Vital Sine then Jason, as it is more clear than the D-D. That was one of the complaints on the D-D at MACNA. I have had both in hand

 

[jason2459]

Thanks for the confirmation. I'm really happy with the D-D. On the redesign I hope they keep the 1/2 markers opposite the full point markers on the scale and the price. It's well worth the cost right now. Again, thanks for all the input.

I think I'll use the Mik for down in the basement to double check my pinpoint probe for my mixing station and use the D-D upstairs for my tanks. When D&D come out with their newer new model I'll have to check it out.

 

[Waterobert]

Boomer, it feels like you like Vital-Sine more then the new D-D design. What about calibration, is Vital-Sine designed for sea water like D-D? I have Sybon and want to upgrade, what would be your choice?

 

[Boomer]

Jason

The idea is to keep the scale the same only it will not be what appears to be cut off. That means the spacing of the lines will be be greater for more accuracy, as the scale will extend more vertical.

Water.

First the Vital-Sine/Vee-Gee is a full scale seawater refract. I also feel it is of better quality. I was disappointed with the D-D and feel they missed the boat and should have done it right the first time. The D-D is Chinese and the Vital-Sine/Vee-Gee is Japanese. And the Japanese are leaders in refracts and the Chinese are the worst. And neither are what I will call full blown Lab Grade seawater refracts. That is a Japanese Atago and is way to costly, at $250. And there is also the famous German Kruss but they do not have a seawater refract but if they did would approach at least $150 or more The Cadillac of all refracts is the Misco Digital Seawater refract ~ $500. The Vital-Sine/Vee-Gee $90 - $100.

 

[Waterobert]

Thanks Boomer, I will get Sine/Vee-Gee.

 

[jason2459]

The vitalsign is a very sold piece of equipment and I really wish I quesioned what I was looking at earlier when it was still under a warranty. You should be very happy with it.

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[jason2459]

Finally got a replacement Vital sign(Veegee) from DFS. WOW, night and day difference. Very bright and very easy to read the line even better then the D-D. Calibration to 0 with RO/DI matches right up to 35ppt when verified with 53mS pinpoint solution unlike the D-D refract. Makes me still kick myself in the rear I didn't complain about the vital sign when I first got it because DFS is usually really good about quality control and replacing defective merchandise they sell. I still like the ease of use of the Milwaukee. I'll probably end up using the Vital sign to check the salinity in the sump for my main tank down in the basement and double check the pinpoint salinity probe for the mixing station and then I'll use the Milwaukee upstairs for my mantis tank. Keep the DD as a backup in case something breaks but can't see myself using it now that I have a Vital Sign in good condition.