Help! Should I trust my old swing arm or new refractometer?

[singmealullaby]

I need some help guys,

 

I just picked up a new refractometer from dfs, the cheapest one they had, and it's telling me my specific gravity is at 1.028, when my old swing arm tells me 1.024? what should i do? my tanks been running fine so far, so should i lower my SG to 1.025 according to the new refractometer? Thanks in advance for any advice, i don't know what to do.

[Lalani]

Did you calibrate the refractometer before using it?

[dtfleming]

Do u have any distilled water? if so drop some on the refractometer to see if it reads zero. I would bet the refractometer is correct.

[singmealullaby]

i calibrated with my ro/di water, would that be ok? i waited 2 minutes for the temperature to stabilize and still get the same readings...?

[OceanNano]

Do u have any distilled water? if so drop some on the refractometer to see if it reads zero. I would bet the refractometer is correct.

 

+1 use the distilled water thing and see. I just got my cheap ebay refractometer and had the same issue with the old swing arms and FALSE lows.

[masterbuilder]

Never trust a swing arm against a calibrated refractometer. The distilled water thing will get it very close.

Next time you order something get some 53ms cal fluid, its cheap and will read 1.026 on a calibrated refracto.

[GrandeGixxer]

+1 for the calibration fluid.

[singmealullaby]

thanks guys, i'll try the distilled water and then order some calibration fluid. for now i'll just keep the sg the same since everything is doing ok. i wish i never bought this thing! ignorance is bliss.

[OceanNano]

. i wish i never bought this thing!

 

Don't hate the refractometer it's probably correct....and you have some water to adjust.

[masterbuilder]

Yeah...no biggie, just mix your next water change slightly lower, like 1.024/.023. That will drop it slightly

[Weetabix7]

Trust the refractometer.

Lower your salinity/SG gradually, don't do it all at once.

[constantocean]

natural seawater is usually around 1.030, hence why your tank is doing okay at 1.028

however you probably still want to lower it to around 1.024-1.026

the refrac is probably correct, hyrdrometers are infamous for being off.

[mhc]

I wouldnt trust a nondigital refractometer that cant autocalibrate itself. The best on the market is the Palm Abbe digital by Misco: http://www.misco.com/products/AQUAR-H20.html.

[scokill]

I wouldnt trust a nondigital refractometer that cant autocalibrate itself. The best on the market is the Palm Abbe digital by Misco: http://www.misco.com/products/AQUAR-H20.html.

 

 

Huh????

[SeeDemTails]

natural seawater is usually around 1.030, hence why your tank is doing okay at 1.028

however you probably still want to lower it to around 1.024-1.026

the refrac is probably correct, hyrdrometers are infamous for being off.

 

You know I am surprised that someone hasnt questioned you yet, lol. I have noticed the same thing all the time, the NSW around daytona beach is around 1.029 on my refractometer.

[badbread]

I just got a refractometer from marinedepot and was using a swing arm prior to it. The swing arm was off by about .003

[SPS20]

You know I am surprised that someone hasnt questioned you yet, lol. I have noticed the same thing all the time, the NSW around daytona beach is around 1.029 on my refractometer.

 

It tends to be higher closer to shore, but a point or two lower than that out on the reefs, if I am not mistaken. This is because of all the seawater that evaporates at the shore. leaving salt in the sand which re-dissolves with the wave action.

 

I have heard, but cannot confirm that you would get lower readings if you were to take some water from 100 yards or so out from shore.

 

Calibrate and trust the refractometer, and chuck the swing-arm, imo.

 

Just my .02,

-Josh

[Pship]

I agree. The refractometer is the best thing you can use.

[fish02]

Randy Holmes-Farley is where it's at when you need info on anything reef related. This is an article all about refractometers:

 

http://reefkeeping.com/issues/2006-12/rhf/index.php

 

The order of accuracy in specific gravity measuring devices are as follows (specific gravity measurers):

 

Swing arm = crap

Refractometer

lab grade Hydrometer

 

and finally the best and what I use (measures conductivity of the saline solution):

 

Conductivity meter

 

The last one is used by researchers and the like.

 

I believe a better way to calibrate a refractometer is to use American Marine 53 micro siemen calibration solution. That is an equivalent specific gravity reading of 1.0260 (I can't remember the last number)

 

Oh and weather you get a digital refractometer or a analog one they both are going to have about the same accuracy.

[scokill]

Can't imagine needing a digital refractometer to get to .0000 acuracy. Even if the accuracy of analog is +/- .001 that's 1.025 vs. 1.024 or 1.026, irrelevent. Spend the money somewhere else....

[Coast]

New Refractometer

[archx]

I hope the OP doesn't mind me posting here since I have a similar problem. First off, I'm still very new to reefing, but I have a good understanding of many of the terms, tests and procedures needed to maintain a tank.

 

I have (2) Red Sea hydrometers and they each measures 1.025 for my salt water, both in my mixing water and the water in my tank.

 

I started using a Captive Purity refractometer and calibrated it using the Pinpoint 53.0 ms calibration fluid. I added the fluid then calibrated the refractometer to 53 ms on the scale. Next I tested the tank and salt water mix, and they came out to around 1.045.

 

I know I should trust the refractometer, but has anyone seen this kind of descrapency before?

[filefish949]

not this again..

 

[flame suit on]

 

let me just start by saying, refractometers are super cool, and neat and all

 

they have some problems, I do not wish to spend the money on a conductivity meter, so i use a swingarm

 

 

do not calibrate your refractometers with RO/DI water, there is about a 90% chance it will be good

 

if you want to use the super cool "beam me up Scotty" looking refractometers, spend the extra $10.00 and get a few packets of .35ppt calibration fluid.

 

I do not care what MD says, or the instructions say, if you calibrate your refractometer with RO/DI, there is a fair chance that your swingarm is more accurate

 

the other thing you have to be mindful of is your magnesium levels and here is why:

 

neither a hydrometer or a refractometer measure salinity, which is what we are interested in

 

a hydrometer measures specific gravity or the weight of the water which is affected by all dissolved compounds in the water, the VAST majority of which, water aside, is sodium chloride, whether that specific gravity, it predicts your salinity

 

a refractometer measures refractive index of liquids, in seawater, sodium chloride is the largest contributor, however magnesium has a higher refractive index than sodium chloride and can have a measurable impact on the solutions refractive index, which the refractometer uses to predict salinity

 

either way, there have been several studies of the accuracy of swingarms and when properly maintained, they are surprisingly precise

 

to maintain a swingarm, just soak some vinegar in them a couple times a year

 

 

 

 

 

I started using a Captive Purity refractometer and calibrated it using the Pinpoint 53.0 ms calibration fluid. I ?

 

 

 

is the Pinpoint 53.0 ms in a gold package? if so it is only for calibrating conductivity meters, stick with teh hydrometers until you can get some 35ppt solution

[ChrisP]

I'd bring them both (along with some water) in to the LFS to be sure you're calibrating and reading the refractometer corrrectly and to see what reading they get on their equipment. I have an old Coralife "swing-arm" and it's ALWAYS consistent with my refractometer readings.

Chris

[bdare]

I'd bring them both (along with some water) in to the LFS to be sure you're calibrating and reading the refractometer corrrectly and to see what reading they get on their equipment. I have an old Coralife "swing-arm" and it's ALWAYS consistent with my refractometer readings.

Chris

YEAH.... cause all the people that work at the LFS know what they're doing...