Help with salinity...different readings

[Detroit_aqua]

Hi all. Newer to the saltwater hobby. I have a refractometer and a hydrometer. I do have reason to believe I may have over done it on salt when filling the tank. My refractometer which is about a year old gives me a reading of 42ppm, but my brand new hydrometer gives me 35ppm on the dot. How can I tell which is accurate?

Also worth noting that when I first filled the tank and added salt, for the week after I was actually getting readings of less than 35ppm...so Idk what to believe.

 

[Dr. Phil]

Hi! Hydrometers are notorious for giving incorrect readings. Have you calibrated your refractometer? I would be more likely to trust the refractometer than the hydrometer especially if the refractometer has been calibrated.

 

[Detroit_aqua]

the refractometer has not been calibrated since purchase. how do I do so? is there a fluid or something to purcahse

 

[Dr. Phil]

Yep. Buy calibration fluid and calibrate with that.
Something like this:

Refractometer Calibration Solution

Keep your refractometer readings accurate! A refractometer is easily one of the most important tools to have if you own a saltwater tank. Without a refractometer, we would be guessing at how much salt is in the water, and more than likely would not be correct! Even if you have a refractometer...

www.bulkreefsupply.com

 

[W1ngz]

What type of hydrometer? Plastic or a good quality glass one with a cylinder?

 

[Detroit_aqua]

What type of hydrometer? Plastic or a good quality glass one with a cylinder?

Instant ocean plastic

 

[Phil D.]

Hydometers are whale poo!! When you calibrate the refractometer, trust it.

 

[W1ngz]

Instant ocean plastic

;Vomit

 

[Detroit_aqua]

Okay, so to sum this up. My refractometer was reading 42ppm. I had two cheap petstore hydrometers that read 35ppm. My apex probe also read 40ppm and that was a day after calibration. I did a target salinty calculation on two of those sites floating around that do so. I did a 20gal wc with RO water. Now my probe is reading 28ppm, my hydrometers reading 29, but my refractometer is reading 35.....I'm lost. so much descerpancy. Any advice on how to find a real value is appreciated. Thanks.

 

[Reef-Tank]

let your probe sit in the tank for 1 week and re-check salinity again. that way fresh OR water can desolved completely for you to read more accuracy

 

[Randy Holmes-Farley]

the refractometer has not been calibrated since purchase. how do I do so? is there a fluid or something to purcahse

What hydrometer? It is likely much more accurate than an uncalibrated refractometer unless it is just broken. I think you are mostly likely OK.

Calibration fluid is the long term answer for the refractometer, but short term, since you may possibly be in an emergency high salinity problem situation, use fresh water to calibrate it to zero, and if it is still above 40 ppt, I'd consider starting the process of slowly lowering it.

 

[Randy Holmes-Farley]

Stop everything. You are likely causing more problems than you are helping with massive water changes with RO water. That is not the way to lower salinity, and it is likely way to low now.