ATI ICP - Salinity Issues

[jsbzcmcdaniel]

Guys - I just received my ATI ICP test back and it shows my salinity at 31.7 or 1.0239sg. This is the second of three I sent that shows low salinity. I am using three sources to check my salinity and I can't figure out why ATI is showing it so low. I am using my APEX, Hanna Salinity Tester (just calibrated again) and two hand held refractometers. Each time I use the refractometers I calibrate them with RO water. If I use the handheld refractometer I read 35sg but when I use the Hanna tester I get 33sg. The Hanna tester is much closer to the ATI ICP test. I am having SPS issues with little to no polyp extension so I am wondering if the ICP is accurate. Anyone else using ATI for their ICP test and get wierd salinity readings or are my refractometers (1yr old & 1 week) old trash?

 

[GabeM]

Don't calibrate with RO water - buy a calibration solution! the ATI ICP is relatively accurate in my experience.

 

[alysak6075]

You are calibrating the refrectometers wrong. DO NOT USE RO water, you need calibration solution for that.
My ATI ICP was right on the money for salinity

 

[jsbzcmcdaniel]

So I should not use RO water to calibrate the refractometer to zero it out?

 

[Randy Holmes-Farley]

So I should not use RO water to calibrate the refractometer to zero it out?

Not unless it is a true seawater refractometer (usually more expensive and they always indicate so), and even then, a standard is better.

Most refractometers sold to hobbyists are not made for seawater, but for sodium chloride brines, so do not read seawater correctly if calibrated in RO/DI.

 

[Miller535]

So I should not use RO water to calibrate the refractometer to zero it out?

No, use calibration solution.

Best practice is to calibrate every time you use it (I only use mine when mixing a new batch of water), and ALWAYS calibrate it and measure your water in a well lit area. It will read different if the room you calibrated it in is different then the room you are using it in.

 

[jsbzcmcdaniel]

Not unless it is a true seawater refractometer (usually more expensive and they always indicate so), and even then, a standard is better.

Most refractometers sold to hobbyists are not made for seawater, but for sodium chloride brines, so do not read seawater correctly if calibrated in RO/DI.

WOW! I am a total noob and have been doing this for 20+ years. This was the method a local reefer taught me when I first bought my refractometer and moved away from the swingarm style. Unreal! I just ordered some calibration solution. I assume I can't use the calibration solution for the apex probe to calibrate the refractometer??

 

[alysak6075]

So I should not use RO water to calibrate the refractometer to zero it out?

I use this (hasnt led me astray yet): https://www.bulkreefsupply.com/refractometer-calibration-solution-brs.html

 

[vetteguy53081]

For right now, I would take a water sample to a trusted LFS and see what reading they come up with

 

[Miller535]

WOW! I am a total noob and have been doing this for 20+ years. This was the method a local reefer taught me when I first bought my refractometer and moved away from the swingarm style. Unreal! I just ordered some calibration solution. I assume I can't use the calibration solution for the apex probe to calibrate the refractometer??

I wouldn't. The apex probe is a conductivity probe, not a refractometer.

 

[AbjectMaelstroM]

Milwaukee digital refracometer is calibrated with RODI water. Not sure how many others do the same.

I calibrate using RODI water then rest BRS calibration fluid and it reads 1.026.

 

[Randy Holmes-Farley]

Milwaukee digital refracometer is calibrated with RODI water. Not sure how many others do the same.

I calibrate using RODI water then rest BRS calibration fluid and it reads 1.026.

Yes, it is a true seawater refractometer. That said, a number of folks also have issues with its repeatability.

One way to tell is how the different scales line up. If 35 ppt matches sg = 1.0264 or so, then it is a true seawater refractometer.

If 35 ppt matches a sg of 1.025 (33 ppt seawater equivalent), then it is a brine refractometer.

 

[User1]

Yes, it is a true seawater refractometer. That said, a number of folks also have issues with its repeatability.

One way to tell is how the different scales line up. If 35 ppt matches sg = 1.0264 or so, then it is a true seawater refractometer.

If 35 ppt matches a sg of 1.025 (33 ppt seawater equivalent), then it is a brine refractometer.

Not that you asked but I'm going to second, third, and prime number what you posted. Which leads me to why I'm even posting. @jsbzcmcdaniel I had a similar issue as you but started first after I lost a couple of fish for some unknown reason. Tank looked OK outside a few algae issues but I couldn't understand why a healthy looking fist died. Anyway I figured I would do similar to you and pick up a ICP test, also from ATI, and send it off. Well, it came back and my salinity was .33 or so. I will have to go back but basically it was lower than what my tools report. I made a post here, @Randy Holmes-Farley and a few others educated me kindly and said to use a reference fluid, and now the tank water matched ATI's results to a T.

As Randy noted above on the Milwaukee I also use a MA887 Seawater Refractometer. It has to be calibrated to its instructions then I use a reference fluid per everyone's recommendation, and now my salinity is always correct. While I like the Milwaukee unit, and mine dates back to 2000, it is off. I'll calibrate it and reference it to .35 ppt and it always reports .2 higher...

Anyway just figured I'd throw my hat in the ring that my ATI results first time around are similar, they are correct, and I learned the proper way to both calibrate and verify before water changes. I don't believe that was the cause of my fish loss but I still learned something new.

 

[ceaver]

Hi all, trying to revive this thread real quick because I'm having a similar issue, in that I just received my very first ICP results ever, from ATI, and they show my salinity being low as well at 31.39. However, I'm using a recently purchased BRS refractometer (which appears to be legit seawater according to Randy's criterion) with the BRS calibration juice. According to that, I'm spot on at 35 ppt. The only possible symptom is low PE on acros, but I have no idea what to believe at this point. Think I may go Trident for my next ICP...
Thanks in advance for any info!

 

[alysak6075]

Hi all, trying to revive this thread real quick because I'm having a similar issue, in that I just received my very first ICP results ever, from ATI, and they show my salinity being low as well at 31.39. However, I'm using a recently purchased BRS refractometer (which appears to be legit seawater according to Randy's criterion) with the BRS calibration juice. According to that, I'm spot on at 35 ppt. The only possible symptom is low PE on acros, but I have no idea what to believe at this point. Think I may go Trident for my next ICP...
Thanks in advance for any info!

Hold up. There is a seawater refractometrr and a saltwater refractometer. They are calibrated differently. Google around to see what is the proper procedure for yours. Maybe post a link which one u have.

 

[Shirak]

Hi all, trying to revive this thread real quick because I'm having a similar issue, in that I just received my very first ICP results ever, from ATI, and they show my salinity being low as well at 31.39. However, I'm using a recently purchased BRS refractometer (which appears to be legit seawater according to Randy's criterion) with the BRS calibration juice. According to that, I'm spot on at 35 ppt. The only possible symptom is low PE on acros, but I have no idea what to believe at this point. Think I may go Trident for my next ICP...
Thanks in advance for any info!

The refractometer on BRS website states not to use RO/DI for calibration so doesn't that indicate it is a brine refractometer and not a true seawater refractometer? Either way if you use the proper calibration solution it should work I would think. Not sure why your ICP showed your salinity low compared to your calibrated refractometer. Can you have a LFS double check? You could also try mixing up some of Randy's DYI refractometer calibration solution as a second check. Maybe the refracto juice is off?

 

[minus9]

If your calibration solution tells you to shake before use, then it’s not a trusted solution. Brightwell’s calibration solution is garbage and completely unreliable, I’m not sure if BRS’ solution needs to be “mixed” before use, but steer clear of any that require shaking. The only solution I’ve used is Aqua Craft or you can make your own via Randy’s recipe. Aqua Craft My D&D refractometer has been spot on using Aqua Craft and is made for seawater. Also, my old school Tropic Marin glass hydrometer works like a charm.

 

[Shirak]

If your calibration solution tells you to shake before use, then it’s not a trusted solution. Brightwell’s calibration solution is garbage and completely unreliable, I’m not sure if BRS’ solution needs to be “mixed” before use, but steer clear of any that require shaking. The only solution I’ve used is Aqua Craft or you can make your own via Randy’s recipe. Aqua Craft My D&D refractometer has been spot on using Aqua Craft and is made for seawater. Also, my old school Tropic Marin glass hydrometer works like a charm.

According to BRS the Refracto Juice is from Aqua Craft but still doesn't hurt to check with another know solution

 

[ceaver]

The BRS juice does say to shake well before use, which I have. I wasn't aware there was a DIY calibration juice, may try that next. The LFS is good idea as well. I'll report back if anything useful comes to light...

 

[Shirak]

Scroll down to the section on Refractometer standard. Underneath table 2 is the recipe for mixing up some solution
http://reefkeeping.com/issues/2004-06/rhf/index.htm