Check you refractometer

sirrealism

sirrealism

New member
So I have been using this same refractometer for about 15 years or more. I cant remember the last time I checked it. I am guessing 7 or more years. I just used it and thought all is well. I had a hard time keeping high end SPS. Thought it was the LEDs so I switched back to T5s and I will admit the SPS are doing much better. I have been fighting low Mag and having to dose often which I have been through before but never knew why.

This past weekend I dropped my refractometer and could not fix it so I ordered one from amazon. Came last night and I reset it and went around and checked all 6 of my systems. Everyone was between 1022 and 1023!!! I have always kept them at 1026. Hard to keep your numbers up when you don't use enough salt. I know some keep there systems salinity low but I think its hard to keep SPS at such low numbers.

The point is take a minute and check your refractometer. Don't be a dumb *** like me. LOL
 
+1
I went through the exact same thing a few weeks ago. Mg, Ca and DKH all creeping low. Eventually I got some Salifert Refractocheck and hey presto my sg was way down.
 
And a reminder to all, don't calibrate to 0 with freshwater or your refrac will be off when trying to measure saltwater!
 
Another note - it's been previously mentioned to use the same light source to check as the one you calibrated with.
 
zachfishman said:
And a reminder to all, don't calibrate to 0 with freshwater or your refrac will be off when trying to measure saltwater!
Click to expand...

When using for saltwater do you calibrate with a solution? Ive been doing it wrong for a lonnnggg time now I guess. With rodi freshwater to 0...
 
Reefpilot11 said:
When using for saltwater do you calibrate with a solution? Ive been doing it wrong for a lonnnggg time now I guess. With rodi freshwater to 0...
Click to expand...

I've heard plenty of things before about using rodi water as long as you know it's 0tds, although it seemed like this wasn't the preferred choice of methods, but acceptable.

Otherwise just buy a calibrated solution online. I got one that's 35ppt so I just drop the liquid on my refractometer and then line it up with the 35. I actually just checked mine today and it was off by like .002.
 
Kodock said:
Sarcasm?
Click to expand...

I always thought it was accurate to calibrate with RODI, it is 0 ppt isn't it?! But depending on your refrac, the error increases as you depart from the salinity you calibrated at. For example, my refract will show -2ppt when I measure RODI (calibrated with 35ppt solution and verified). I assume the inverse is true (calibrating to zero would result in 33ppt water reading as 35ppt and making you think you're at full salinity). Of course such a difference can be of little consequence, but still... accuracy is nice. :)
 
Ordered some calibration fluid. So we will see how off I've been. Not sure if it will matter much, corals are growing and fish are happy.
 
The new refractometer that I bought said to use 0TDS and set to 0. Still better to set with calibration fluid IMO
 
Mine also said to use 0 TDS RO to calibrate. Was way off when I used 35ppt solution. Subsequently my corals are now doing much better since I adjusted my tank sg up to where I thought it was already.
 
ummmm I could be wrong, but shouldn't your make up water be the same temp as your tank???
 
Kubi said:
ummmm I could be wrong, but shouldn't your make up water be the same temp as your tank???
Click to expand...

??? Yes you should but I miss where we were talking about temp? On the other hand I cant match my temp perfectly because my water change system is in my garage where its 100 degrees most of the time. I use a fan on my NSW to get it close. My systems run at about 79 and I can get my NSW to 80 unless I float my ice packs.
 
thanks for the info. as good as this info is I just ordered "Standard seawater 35 ppt" from amazon.
After reading this article I am happy to pay a few bucks to get a test fluid. "Time is money and I am always short on time"
 
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