refractometer

[ruggirello2]

I didn't calibrate my refractometer for like 4 months and it was way off. When I finally calibrated it, it was 8 points off. I thought my salinity was at 1.026, but it was actually at 1.018. all of my corals and fish are doing fine. How fast should I raise it up.

 

[yellojello]

I'm a rookie, and a few weeks ago, I made a similar mistake of low salinity, and added the salt directly to the sump to raise it up... not good! Remember to make the saltwater separately and do as a water change. luckily I had nothing in the tank but button polyps.

I'm guessing you should bring it up slowly, but not sure how fast either. I'm sure someone with more expertise can chime in.

 

[revhtree]

Raise it slow!!! If they are fine now, then they will be fine to wait as the salinity is raised. I would mix some high salt content top off water and do it that way. I have done it this way as well.

 

[Kbra]

18 to 20 should be just fine and then your in the "safe zone" again. So just get it to 20 then slowly add to where u wanna be over a couple weeks

 

[CookieJar]

I agree w/ Rev, simply use saltwater as topoff until you reach desired salinity.

 

[_Alex_]

yes but remember dont always use saltwater as top off! if u do eventually your salinaty will go threw the roof.


just use salt water till u get it where u want it and as it evaporates use ro- water to top it off, once u get it straightened out u can keep it right about the same spot by topping off every day or 2 and then your salanity will be alot more stable.

 

[RBursek]

Remember to calibrate your refactometer with pinpoint 53 solution and not distilled or DI water.

 

[birdsnest]

what is the margin of error if you were to callibrate with RO/DI?

 

[_Alex_]

Why not use ro?

Remember to calibrate your refactometer with pinpoint 53 solution and not distilled or DI water.

 

[RBursek]

Off by about 3ppt. Because if you use RO/DI you are calibrating it for fresh water, not salt water. Ithttp://reefkeeping.com/issues/2006-12/rhf/index.php is all explained in this article under calibration.

 

[Angels 2010]

Remember to calibrate your refactometer with pinpoint 53 solution and not distilled or DI water.

I had read and heard the same thing, but had been calibrating with ro/di for 9 years with no issues and then decided to calibrate the same refractometer with the solution and got the same results. So I still calibrate with ro/di.

 

[_Alex_]

that makes no since use salt water to calibrate to 0? How would u do that with salt water?

Mine Has been right on so not gonna change something that works

 

[stunreefer]

Why not use ro?

Although the consensus is that refractometers are "really accurate", that's far fetched. Are they more accurate than a $10 swing arm hydrometer? Most of the time yes, assuming they're properly calibrated. The most accurate and cost effective means for our hobby is a lab grade quality floating hydrometer. You have to account for temperature correction, but it's easy as pie.

Regarding calibrating refractometers, as mentioned, calibrate with 35 ppt solution, not RO/DI water. The refractometers sold for the hobby aren't all that great, and they have a HUGE range on them. When calibrating with RO/DI you're calibrating to the lowest possible range of the unit, when we're trying to measure a level that's about halfway up the units scale. Most of the time the reading is considerably skewed halfway up the scale if calibrated to the low end, I've seen it well over 5 ppt off before (all are different, some are pretty close, most are not). By calibrating to the mid range we get the best accuracy.

 

[Angels 2010]

that makes no since use salt water to calibrate to 0? How would u do that with salt water?

Mine Has been right on so not gonna change something that works

while i don't feel the solution is necessary, you aren't calibrating to 0 you are calibrating to 35 ppt.

 

[_Alex_]

Although the consensus is that refractometers are "really accurate", that's far fetched. Are they more accurate than a $10 swing arm hydrometer? Most of the time yes, assuming they're properly calibrated. The most accurate and cost effective means for our hobby is a lab grade quality floating hydrometer. You have to account for temperature correction, but it's easy as pie.

Regarding calibrating refractometers, as mentioned, calibrate with 35 ppt solution, not RO/DI water. The refractometers sold for the hobby aren't all that great, and they have a HUGE range on them. When calibrating with RO/DI you're calibrating to the lowest possible range of the unit, when we're trying to measure a level that's about halfway up the units scale. Most of the time the reading is considerably skewed halfway up the scale if calibrated to the low end, I've seen it well over 5 ppt off before (all are different, some are pretty close, most are not). By calibrating to the mid range we get the best accuracy.

Ok that makes more since. Considering its same concept on calibrating a ph monitor for higher ph use 7 and 10. So where can I get solution for salinity

 

[stunreefer]

Considering its same concept on calibrating a ph monitor for higher ph use 7 and 10.

Exactly :nerd:

So where can I get solution for salinity

Many vendors carry it, but you can get it here: Aquarium Testing Solution: American Marine Inc. 53.0 mS Calibration/Reference Fluid

You can also make your own pretty easily, instructions are in the Reefkeeping artciel linked earlier in the thread.

 

[Angels 2010]

marine depot has it also...

 

[_Alex_]

Ok thanks

 

[RBursek]

The article I posted has a home made recipe for a calibration solution that I have made and used/tested against pipiont 53 and was almost spot on, it is at the end of the article.

 

[ruggirello2]

How often should a refractometer be calibrated, and just for the record I do use the pinpoint calibration fluid, not ro/di water.