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Old 04/17/2019, 01:26 AM   #1
PCguy21
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Why does my refractometer alwats have to be calibrated

So question is in the thread title.. im doing hypo and i noticed my refractometer always has to be recalibrated. Is it temperature based or something ? Like my room can be 80f one minute then 72f the next so i dunno.

But im doing hypo in my tank and i have BRS refracto juice fairly new bottle and cap has always been on after. Like tonight i changed 50% of my water put in the exact amount of cups of salt i know it takes to bring it back to 1.08 and sure enough it was 1.08 after the tank mixed around for an hour or so.

Then i played some video games. And 3 hours later i checked the tank... it said it was at 1.06. I checked the refracto juice and it said 1.024 so recalibrated back to 1.0264 which in the middle ofr 26 and 27. Checked my tank and its at 1.08 like i left it.

Why does ny refractometer always do this ? Every day it has to be checked with the refracto juice so i know for sure what the salinity actually is.

Is this normal ? Is it room temperature based or something ?


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Old 04/17/2019, 02:03 AM   #2
Tastee
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This is normal and yes it is temperature based. I just recalibrate mine with tap water before each use. Its not as good as calibrating with 35 ppt solution but Im after stability not 100% accuracy so that is not an issue for me.


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Old 04/17/2019, 03:35 AM   #3
PCguy21
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Ok just makin sure... normally i wouldnt care but i need it to stay at 1.08


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Old 04/17/2019, 05:50 AM   #4
devastator007
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My refractometer has been unstable lately as well. Seems it needs adjusted +/- 2 ppt either way from day to day. Used to be more stable, so not sure what's been making it less stable lately. Perhaps the changing weather? I also now check and adjust calibration before each use to ensure it's reading right. Has saved me from making salinity adjustments that would not have been necessary.

Would be nice to get one of those digital ones if you can justify the cost.


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Old 04/17/2019, 06:37 AM   #5
ducati1212
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Mine was doing the same thing. It was off every time and I had to calibrate. Off by allot I would test it would be 1.021 so I would calibrate need to adjust re test 10 minutes later 1.028.

I bought a Hanna salinity tester and its been great. Assuming its reading right its been great that is. and if its not im in happy ignorance.


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Old 04/17/2019, 02:47 PM   #6
dadnjesse
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I have three refractometers one is an expensive VeeGee and they all differ. Then I bought the Milwaukee Digital one. It has been the most stable refractometer out of them all.


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Old 04/17/2019, 03:46 PM   #7
outssider
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Quote:
Originally Posted by PCguy21 View Post
Is it temperature based or something ?
They can be very temperature sensitive always calibrate right before use.


You are going to have a problem trying to get 1.08 salinity...if you calibrate with 1.026 fluid and are testing water that's at or close to 1.026 your going to be accurate. If you're sample is close to -0- you want to calibrate with ro/di water...but your sample is at 1.08...ideally you would want to calibrate at 1.08....you might be better off calibrating with ro/di water because that is a lot closer to your sample of 1.08....


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Old 04/17/2019, 04:38 PM   #8
PCguy21
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They can be very temperature sensitive always calibrate right before use.


You are going to have a problem trying to get 1.08 salinity...if you calibrate with 1.026 fluid and are testing water that's at or close to 1.026 your going to be accurate. If you're sample is close to -0- you want to calibrate with ro/di water...but your sample is at 1.08...ideally you would want to calibrate at 1.08....you might be better off calibrating with ro/di water because that is a lot closer to your sample of 1.08....

I dont have ro di water
I use tap water to fill mytanks. Never had an issue with that. I live ina townhouse so i cant store 200 gallon drums like some people do lol

I can buy some distilled water. Would that work ? Tbh id think distilled is more pure then since its evaporated water.

And fyi testing with mytap watee after refracto juice 1.026 it reads 1.001. So my tap is pretty close to 0.

Ill get some distilled and check it with that.. but are you sure about this because i was told even for hypo to use calibration fluid.



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Old 04/17/2019, 05:34 PM   #9
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Calibrating either way will work, but as was stated, if your temp is fluctuating that much, you'll definitely need to calibrate before you use it every time.

On another note, are you mixing the salt water in the actual tank, or are you doing it before and then adding it? Be careful adding salt to a tank that already has livestock in it - can be very dangerous.

As far as RODI, you don't need drums. I also live in a small place, all I do is set up my RODI whenever I need to make water. When I'm making salt water, I typically set up a container for the night, make the water and mix it, then change about 24 hours later. Then everything gets stored up until the next use. Fairly easy and an RODI is definitely worth the investment. Even if Tap Water is getting you by currently, it doesn't mean it always will. But knock on wood that it keeps working for you!


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Old 04/17/2019, 09:10 PM   #10
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re you sure about this because i was told even for hypo to use calibration fluid
ideally you want calibration fluid that is 1.08....but I don't think that exists, you could make your own but that would be expensive if you don't have the proper equipment (scale).if it were me, and I had to choose between distilled and 1.026 calibration fluid ...I'd choose distilled because it is closer to 1.08


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Old 04/17/2019, 09:25 PM   #11
PCguy21
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Well distilled is showing 8n the negative by 2 points so 1.08 is 1.010 accroding to it..

So what should i trust refracto juice qt 1.08 or distilled... one of them is off by 2 points.. and id hate to go to 1.06 lol if its really 1.08 but also 1.010 is kimda pushing it. Although 1.010 seems to work for my ich issue if it is 1.010.

Edit: i take that back.. after 2 min the distilled showed 1.000. Tap water showed 1.001 so it seems the refracto juice is no different then distilled water lol.. or even tap water... what a scam lol



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Old 04/17/2019, 09:28 PM   #12
PCguy21
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Calibrating either way will work, but as was stated, if your temp is fluctuating that much, you'll definitely need to calibrate before you use it every time.

On another note, are you mixing the salt water in the actual tank, or are you doing it before and then adding it? Be careful adding salt to a tank that already has livestock in it - can be very dangerous.

As far as RODI, you don't need drums. I also live in a small place, all I do is set up my RODI whenever I need to make water. When I'm making salt water, I typically set up a container for the night, make the water and mix it, then change about 24 hours later. Then everything gets stored up until the next use. Fairly easy and an RODI is definitely worth the investment. Even if Tap Water is getting you by currently, it doesn't mean it always will. But knock on wood that it keeps working for you!


Tabk is too large to do 50 gallons by 5 gallon buckets.. and since it needs to go up only 0.004 points i do it by a little container.. mix it pour some in let it mix in the tank.. mix it.. pour some in ect.. Hasnt cause any issues.. now i wouldnt do that if i were at 1.026 and did a 50% water change.. id do it the hard way.

But i hear what your saying.


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Old 04/18/2019, 07:53 PM   #13
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If it hasn't been stated already, take 2-3 readings to make sure the first isn't a fluke. I often find that between 2, 3, or even 4 readings one will be off (maybe some dried salt on the slide the first time, etc).


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Old 04/18/2019, 08:54 PM   #14
Kevin Guthrie
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Question: if you don't have any RO/DI or distilled, what are you doing to clean the refractometer after each use? Anything left to dry on the prism and cover surfaces will mix back into your sample next time and make it read saltier.


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Old 04/19/2019, 01:09 AM   #15
PCguy21
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im using tap water or my breath and a clean cloth, i just tested my tap its 1.01 and distilled is 1.00 and the refracto juice shows 1.026 after i used distilled, so wiping it off leaves no residue


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Old 04/19/2019, 08:52 AM   #16
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"Refracto juice" LOL.

If you have distilled water and 35ppt calibration fluid, then make your own calibration fluid by combining them both.

2 parts distilled water + 1 part calibration fluid = 11.7 ppt calibration fluid or 1.0087 specific gravity.


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Old 04/19/2019, 09:24 AM   #17
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"Refracto juice" LOL.

If you have distilled water and 35ppt calibration fluid, then make your own calibration fluid by combining them both.

2 parts distilled water + 1 part calibration fluid = 11.7 ppt calibration fluid or 1.0087 specific gravity.
Good luck getting that mixed exactly though. You would have to mix a very large batch or have very precise measurement tools to get a reliable mixture.


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Old 04/19/2019, 09:54 AM   #18
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Good luck getting that mixed exactly though. You would have to mix a very large batch or have very precise measurement tools to get a reliable mixture.
Doesn't have to be that expensive or precise...You don't have to use a volumetric flask.

5 mL syringe would work fine (should have those lying around with test kits), and so would a graduated cylinder (a few bucks on amazon).


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Old 04/19/2019, 12:06 PM   #19
PCguy21
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"Refracto juice" LOL.

If you have distilled water and 35ppt calibration fluid, then make your own calibration fluid by combining them both.

2 parts distilled water + 1 part calibration fluid = 11.7 ppt calibration fluid or 1.0087 specific gravity.


I hear ya.. but tbh its easier to spend 5$ wait for it come in the mail... but i just learned distilled and even my tap water are 0 so tbh there is no need to make 1.08 solution.. specially if i calibrate to 0 then use 1.026 solution and it reads at 1.026 that means there is no discrepency in the hypo measurement.


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