hydrometer vrs refractometer

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shark55

Aquarium Advice Newbie
Joined
Feb 16, 2009
Messages
8
hi been running my tank for 7 wks withliverock,inverts and 4 fish everything is doing well. used my hydrometer all this time with a salinty reading at the 1.023 mark. Well today i wanted to insure my investment for my fish one being a purple tang$$$ and bought a refractometer which gave me a different reading of 1.028 which is out of the window so to speak. that is quite a variance. What are the repercussions of the salinty being this high even though the fish are thriving, and how do i correct the salinty level in the proper way? Thanks
 
To correct the salinity remove a small amount of saltwater and replace with ro/di water or whatever fresh water you use during water changes. Be sure to change small amounts, a gallon or two at a time, and that should do the trick. Just check the salinity after replacing with fresh water.
 
Yes, there can be a big difference between a hydrometer and a refractomenter.
 
That actually was about the difference in readings from my hydro to me refracto. I agree, remove some SW and replace with FW.
Mtlion is correct, I would only add don't do a few gallons at a time if you have a small tank.
What size tank do you have?
 
Agree with the others, but also want to add that 1.028 isn't THAT far above where it can be. Granted... FOWLRs often times run lower salinity, but having a salinity of 1.026 is pretty normal for a reef.
 
75g thanks for imput. it was the best 70.00 i spent for a precision reader!
 
Good advice given...Reefractometers are one of the few things that EVERY SW tank owner should have!!

Glad you picked one up!!
 
A refractometer is more accurate, just make sure it's calibrated. You can check the calibration by applying freshwater and making sure it reads 0 . If not adjust up or down.
 
Better yet, get some 53.0 mS calibration fluid meant to calibrate electronic salinity meters. Using it, your refractometer should read 35 ppt, or a little higher than 1.026. That way, you're calibrating in the range you're normally measuring at.
 
If you are using "freshwater", use RO/DI water...distilled water...
 
I have a original sea test specific gravity meter that i have always used for my tank and it reads it as 1.021. Is this something totally different than a hydrometer or refractometer?
 
That my friend is a swing arm hydromenter and it is not as accurate as a refractometer.
 
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