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View Full Version : Wow, get a refractometer


jdc
12/15/2010, 11:00 AM
Just got my first refractometer from BRS, checked my salinity and it was at 1.020. My hydrometer was saying I am at 1.025. I should have spent the $40 earlier.

thegrun
12/15/2010, 11:09 AM
Be sure to calibrate it to check for accuracy. You can pick up calibration fluid at your LFS or online for a few dollars.

Sk8r
12/15/2010, 11:16 AM
YOu can get your lfs to doublecheck calibration, usually; and yes, a swing-arm can be that far off.
Once calibrated, they're very tough, take no batteries, work reliably under any conditions and are THE most valuable instrument you own when you need it---because tank death can result from bad readings. Swing-arms accumulate deposits and get less accurate over time: clean them often in white vinegar.

muppet
12/15/2010, 11:17 AM
My hydrometer has been confirmed by refractometer a number of times to be spot on. I think it's luck of the draw with those things. It might also have a lot to do with your technique (filling, tapping, etc).

Korrine
12/15/2010, 11:24 AM
Be sure to recalibrate it every now and then. It's easy to bump the turn knob on top. Got mine off ebay for about $25 shipped, I think. Came from Hong Kong, if anyone is wanting to try to look it up. I did just buy calibration fluid last spring from one of the major online retailers. Can't remember which one for sure.

http://i248.photobucket.com/albums/gg200/kj23502/sw%20tank/100_5092.jpg

kduen
12/15/2010, 12:40 PM
Pinpoint has a 35ppt calibration fluid that BRS has for like $7.

coralreefhq
12/15/2010, 12:43 PM
Haha yea, it's definitely worth the investment.

seapug
12/15/2010, 12:49 PM
There's even some evidence that our beloved off the shelf refractometers show readings higher than they really are, even when calibrated. That's why I've always found my tank was healthier when I kept my SG up around 1.028-030. Granted this is written by a manufacturer of a new type of refractometer, but it is an interesting article:

http://www.theaquariumsolution.com/specific-gravity-salinity-and-its-measurement

A key point being "When using a conventional ‘saltwater’ or ‘brine’ refractometer for the reef aquarium we must therefore look to achieve a reading of 36.8ppt if our intended salinity is 35ppt or 37.3ppt if our intended salinity is 35.5ppt"

coralreefhq
12/15/2010, 12:50 PM
I personally have a hydrometer, Salinity Probe and the refractometer.
When testing, I try to make sure all the numbers are where they should be, otherwise, I'll end up with a lot of problems.

jdc
12/15/2010, 01:06 PM
The Bulk Reef Supply refractometer came with calibration fluid, automatically adjusts for temperature and was spot on.

Dustin1300
12/15/2010, 01:12 PM
I have one from PA and have loved it since day one. They were smart enough to sink the adjustment screw into the unit rather than a thumb screw on the one above which does not make sense. I'd be double checking with my calibration fluid each time:(

streak
12/15/2010, 01:50 PM
With the ATC brand i got from BRS i always wait 30 seconds to take the reading.. seems more reliable.. expecially since the calibration solution says to wait 45 seconds then adjust knob/screw..

Tradewinds
12/15/2010, 02:03 PM
I have one from PA and have loved it since day one. They were smart enough to sink the adjustment screw into the unit rather than a thumb screw on the one above which does not make sense. I'd be double checking with my calibration fluid each time:(

Dustin, PA has a couple listed on their site, which model did you purchase?

JByer323
12/15/2010, 02:19 PM
Dustin, PA has a couple listed on their site, which model did you purchase?

Not Dustin, but I've been pleased with this one. Linky! (http://premiumaquatics.com/store/merchant.mvc?Screen=PROD&Store_Code=PA&Product_Code=REFRACT-PA-K&Category_Code=)

Probably nicer than the $80 I use for brewing beer.

Dustin1300
12/15/2010, 03:01 PM
JByer323 beat me to the punch. Same exact one I use:)

Dwerbs
12/15/2010, 04:14 PM
this is just one of those things you should really not skimp on.

Dustin1300
12/15/2010, 08:50 PM
this is just one of those things you should really not skimp on.

Agreed. In the grand scheme of things this was less than $50 and comparing that to everything else, that equates to nearly nothing! ;)

Agu
12/15/2010, 10:03 PM
Not Dustin, but I've been pleased with this one. Linky! (http://premiumaquatics.com/store/merchant.mvc?Screen=PROD&Store_Code=PA&Product_Code=REFRACT-PA-K&Category_Code=)

Probably nicer than the $80 I use for brewing beer.

Same one I'm using.

I always check twice if I haven't used the refractometer recently. That's because sometimes I get sloppy and haven't thoroughly cleaned the unit after the last use. It doesn't take much dried salt on the lens to throw off the next reading.

jdc
12/15/2010, 11:07 PM
Stupid question but how does a refractometer work?

JByer323
12/15/2010, 11:15 PM
Stupid question but how does a refractometer work?

Pretty easy to understand article about it... (http://www.ehow.com/how-does_5314561_refractometer-work.html)

Flippers4pups
12/15/2010, 11:26 PM
I've got one from Premium Aquatics this year. Found that a hydrometer i bought not to long ago, (brand new out of the box), was off by .005 SG! Spend the $50, it's well worth it!

jdc
12/16/2010, 08:12 AM
Pretty easy to understand article about it... (http://www.ehow.com/how-does_5314561_refractometer-work.html)

Thanks.

the_real_brian
12/16/2010, 09:17 AM
There's even some evidence that our beloved off the shelf refractometers show readings higher than they really are, even when calibrated. That's why I've always found my tank was healthier when I kept my SG up around 1.028-030. Granted this is written by a manufacturer of a new type of refractometer, but it is an interesting article:

http://www.theaquariumsolution.com/specific-gravity-salinity-and-its-measurement

A key point being "When using a conventional ‘saltwater’ or ‘brine’ refractometer for the reef aquarium we must therefore look to achieve a reading of 36.8ppt if our intended salinity is 35ppt or 37.3ppt if our intended salinity is 35.5ppt"

According to this article my salinity's been low for years...super.

jdc
12/16/2010, 09:46 AM
According to this article my salinity's been low for years...super.

But also according to the article consistancy is key.

cloak
12/16/2010, 02:11 PM
I don't doubt the accuracy of a refractometer, but the floating glass hydrometers & the plastic swing arms can work just as well IMO. It's all human error in the end. It wouldn't make any since to put out a product that doesn't work, especially ones that have been left unchanged for so long. My parents were using a floating glass hydrometer back in the late 70's. Talk about consistency!

FWIW.

joeychitwood
12/16/2010, 02:35 PM
In addition to a good refractometer, I would also recommend a TDS meter as well. You might save a lot of money by not purchasing a new RO membrane before necessary. For some reason, I always thought they were expensive, but they can be had for $25 US.

syrinx
12/16/2010, 02:52 PM
I use a lab grade glass hydrometer- more than accurate enough for the hobby- and is recalabrated by rinsing in fresh water. I can`t say anything good about swing arm types.