Refractometer gone wild

pwreef · 09/17/2012, 07:37 AM

Lately I've had an issue with the Refractometer where I shows very high value on an initial test after I take it out of the box. Then once I do a few tests in sequence it shows the proper calibrated value. It's almost as if some residual salt stays on the glass or in the pipet. I wipe the glass with paper towel and rinse the dropper with fresh water. Still same result. Yesterday I tried this: take it out of the box and test with the 35 ppm test solution, I get 40. Then I test RODI water it's 2. Repeat the 35 Ppm solution it's 37. I did drop it a while back and the glass has a small maybe 1 mm chip in one corner. Does that affect the test? Many thanks for your advice.

Michigan Mike · 09/17/2012, 07:38 AM

I don't know but I would get a new one. Up to you

Mavrk · 09/17/2012, 08:58 PM

If it has automatic temperature correction, then you should wait 30 seconds for it to correct itself before taking a reading. If that doesn't fix it, then either know this to be a problem or replace it. Let us know the results.

Psyops · 09/18/2012, 06:11 PM

+1 on the 30 second waiting period. Especially when you just take it out. Take a sample a just look at the reading over a period of time. (say 1 minute or so) and see what happens. Hope this helps.

Alex

bnumair · 09/18/2012, 06:19 PM

i always swirl the prism part of the refractometer in my tank for 30sec to get prism and tank temp acclimated and then take the reading.

bertoni · 09/18/2012, 08:52 PM

Generally, the temperature of the water sample should conform to the temperature of the device fairly quickly. I don't think swirling the device in the water will have a good effect. The temperature compensation is designed to compensate for air temperature, not the temperature of part of the refractometer.

bnumair · 09/19/2012, 06:23 AM

Quote:

Originally Posted by bertoni

Generally, the temperature of the water sample should conform to the temperature of the device fairly quickly. I don't think swirling the device in the water will have a good effect. The temperature compensation is designed to compensate for air temperature, not the temperature of part of the refractometer.

i am not sure on the science here but my lab/setup is in garage and oklahoma heat makes it 130F plus in the garage. if i was to take a sample of 78F from my tank and read it it would be off the chart. AFter swirling it in tank water for few i take the reading its dead on. I have a handheld and a digital refractometer and they all do the same thing. Unless cooled off to under 85F they wont show proper readings.

pwreef · 09/19/2012, 07:44 AM

I don't think temperature is the issue here. I did these tests using the tiny bottle of test solution that was sitting right next to the Refractometer. I waited 1-2 minutes. The reading does not change from the time I put the drops on. The reading changes only when several tests are done in sequence. Then it stabilizes. I guess if no one had a similar issue time to get a new one.

bertoni · 09/19/2012, 07:19 PM

Okay, if the refractometer was at 130 F, I wouldn't expect it to be accurate.

Dipping it in the water might help in that case. I personally would keep the refractometer at a normal house temperature.

As far as the original post, I don't know what's happening, but I'd ditch the refractometer.

09/17/2012, 07:37 AM	#1
pwreef Registered Member Join Date: May 2011 Location: New York Posts: 585	Refractometer gone wild Lately I've had an issue with the Refractometer where I shows very high value on an initial test after I take it out of the box. Then once I do a few tests in sequence it shows the proper calibrated value. It's almost as if some residual salt stays on the glass or in the pipet. I wipe the glass with paper towel and rinse the dropper with fresh water. Still same result. Yesterday I tried this: take it out of the box and test with the 35 ppm test solution, I get 40. Then I test RODI water it's 2. Repeat the 35 Ppm solution it's 37. I did drop it a while back and the glass has a small maybe 1 mm chip in one corner. Does that affect the test? Many thanks for your advice. __________________ Since May 2011: OLD: 57G rimless NOW: ELOS 120, DIY LED using reefll.com 12-up boards

09/18/2012, 06:11 PM	#4
Psyops Still Learning Join Date: Mar 2011 Location: Where my wife decides Posts: 714	+1 on the 30 second waiting period. Especially when you just take it out. Take a sample a just look at the reading over a period of time. (say 1 minute or so) and see what happens. Hope this helps. Alex __________________ GOT REEF! One tank short of a trial separation. Current Tank Info: 180 Gallon reef. Just starting to convert to mainly SPS.

09/18/2012, 06:19 PM	#5
bnumair Dr. Reef at ur service Join Date: May 2009 Location: Tulsa, Ok, USA Posts: 7,751 Blog Entries: 15	i always swirl the prism part of the refractometer in my tank for 30sec to get prism and tank temp acclimated and then take the reading. __________________ Water Quality: NO3 0,Phos 0,Cal 440,Alk 7.5,Mag 1300 "Reef Fast, You Crash, Reef Slow, You Pass" Mike's Reef 3:16 Current Tank Info: 350g DT,95g sump, 50g Frag tank, 4800gph return 4x Sea swirls. 6x AI Vega Color. 200# Pukani rock, dual recirculating skimmer, Biopellet, GFO Carbon rx's, Cal rx. Closed loop. 1.5hp chiller, genesis renew. Apex & RKE

09/18/2012, 08:52 PM	#6
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	Generally, the temperature of the water sample should conform to the temperature of the device fairly quickly. I don't think swirling the device in the water will have a good effect. The temperature compensation is designed to compensate for air temperature, not the temperature of part of the refractometer. __________________ Jonathan Bertoni

09/19/2012, 07:44 AM	#8
pwreef Registered Member Join Date: May 2011 Location: New York Posts: 585	I don't think temperature is the issue here. I did these tests using the tiny bottle of test solution that was sitting right next to the Refractometer. I waited 1-2 minutes. The reading does not change from the time I put the drops on. The reading changes only when several tests are done in sequence. Then it stabilizes. I guess if no one had a similar issue time to get a new one. __________________ Since May 2011: OLD: 57G rimless NOW: ELOS 120, DIY LED using reefll.com 12-up boards

09/17/2012, 07:38 AM	#2
Michigan Mike Freedom costs a buckofive Join Date: May 2012 Location: Michigan Posts: 3,002	I don't know but I would get a new one. Up to you

09/17/2012, 08:58 PM	#3
Mavrk Registered Member Join Date: Jul 2007 Location: California - South Bay Area Posts: 2,775	If it has automatic temperature correction, then you should wait 30 seconds for it to correct itself before taking a reading. If that doesn't fix it, then either know this to be a problem or replace it. Let us know the results.

09/19/2012, 07:19 PM	#9
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	Okay, if the refractometer was at 130 F, I wouldn't expect it to be accurate. Dipping it in the water might help in that case. I personally would keep the refractometer at a normal house temperature. As far as the original post, I don't know what's happening, but I'd ditch the refractometer. __________________ Jonathan Bertoni