do I trust my refractometer?
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Category: Specialized Discussion
Forum Name: Equipment
Forum Description: This is the place to ask question about reef equipment.
URL: http://www.utahreefs.com/forum/forum_posts.asp?TID=46881
Printed Date: July 24 2026 at 3:46am
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Topic: do I trust my refractometer?
Posted By: Davidwillis
Subject: do I trust my refractometer?
Date Posted: February 16 2011 at 10:04pm
| I got a refractometer not too long ago, but it is not very close to what my hydrometer reads. I have two hydrometers one deep six, and one aquarium systems one. They both read my tank is at 1.021-1.022. However my refractometer reads 1.026. This is after calibrating it using RO water. So which do I use? |
Replies:
Posted By: Nick801
Date Posted: February 16 2011 at 10:11pm
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refractometer if your really worried compare it with a second refractometer but I would place bets on the refractometer being more accurate
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Posted By: davser
Date Posted: February 16 2011 at 10:46pm
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i agree the refractometer is way more accurate and you dont have to place water on it two or three times to get an accurate measurement like the hydrometer ------------- It's not about what you know but about who you know |
Posted By: Ryan Thompson
Date Posted: February 16 2011 at 11:10pm
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Refractometer for sure. Quick story for about 2 weeks ago. My Dad's tank was having some issues but we couldn't figure them out. The Big Three elements were on target and flow and lighting are no problem. His HUGE rock of Armor of God palys were all shriveling and dying off. They have been in the tank for 3 years with ZERO issues. Well I sold my tank and took him some of my reefing stuff which included my refractometer. His hydrometer tested the water at 1.023 and I have calibrated the hydrometer plenty of times. It always read a tiny bit low so we thought his salinity was fine and not the issue. Well we took out the refractometer and checked it out, 1.032! I immediately changed 5 gallons of water and brought it down to 1.025. Within about a week the palys started coming back and everything opened up even bigger than before. Hydrometers are pointless in this hobby when it comes to my tanks. They change daily depending on their mood. 1.026 is a great level to be at though! Leave it there and trust your refractometer.
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Posted By: Davidwillis
Date Posted: February 17 2011 at 12:38am
| Thanks, that is what I thought. It was just that both hydrometers were reading the same thing that threw me off. I have been using those hydrometers and keeping it at 1.025 all along, but I guess it has really been at 1.030... |
Posted By: Mark Peterson
Date Posted: February 17 2011 at 12:04pm
Sorry to hear about your tank's high salinity.  Hydrometers are very accurate and reliable. They must be kept clean and free of calcium deposits. Here is something that is generally and unfortunately not known about Hydrometers. Like Refractometers, they also must be calibrated. Have you checked your hydrometers with RO water? Actually that's not too good, since the swing arm is already near the bottom, it's hard to know how far off it's reading. Instead, heck the hydrometer with a known calibration fluid. Saltwater that has a known and verified salinity is easy to find or you can make your own calibration solution with table salt and RO water. The formula is online. First clean the Hydrometer and then simply use a permanent marker to write how much to add or subtract from the swing arm reading. If it is rinsed in tapwater after each use and cleaned every few months it will last forever and be totally accurate forever. (and all for $12 rather than $60  )Clean the hydrometer by pouring in some white vinegar and letting it sit for 10 minutes then rinse in tapwater. ------------- Reefkeeping Tips, & quick, easy setup tricks: www.utahreefs.com/forum/forum_posts.asp?TID=9244 Pay it forward - become a paid WMAS member 
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Posted By: Adam Blundell
Date Posted: February 17 2011 at 12:35pm
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You are welcome to swing by my place to calibrate it. Adam ------------- Come to a meeting, they�re fun! |
Posted By: Davidwillis
Date Posted: February 17 2011 at 3:06pm
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Thanks... I will try makeing a known solution and see how they read. I have never cleaned them but always rinse them out after each use. Actually I have only used the deep 6 a little, and mostly use the other one. The deep 6 does not read down to zero (it stops at 0.010), but I have put ro water in the other one, and it is off (I have to tip the hydrometer to get the arm to move up to zero). Thanks Adam, I would but you are a ways away... I will try making up a solution like Mark said. BTW, my refratometer was only $25... which makes me wonder too.. Maybe it is not a very good one....
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Posted By: philhender
Date Posted: February 17 2011 at 6:08pm
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My opinion... while accuracy is desired, I'd pick one and use it exclusively. Salinity is important, but if your close in salinity levels... consistency is more important. My $.02.
------------- I asked the Lord for the blessing of Patience... he gave me 6 kids! 125g Reef / 55g Sump-Fuge |