Hydrometer Question


New member
I have a Corallife Deep Six Hydrometer. The "safe" range on the hydrometer is marked from about 1.020 to 1.023.

I've noticed that many people in here seem to recommend 1.024 to 1.025 range.

Is the Hydrometer just not tempature corrected (like 1.022 is really 1.024) or is the range they suggest as safe just really off by that much?

As always, I'm very confused!




New member
I believe NSW is between 1.026 and 1.027. About hydrometers, they are not the most exact measurement systems. I would suggest that you get a refractometer. I had the exact same hydrometer and it said my water was at 1.025. However, things in my tank just didn't seem right. So i got a refract and it said my salinity was 1.030! I brought the salinty down and everything looked wonderful!


New member
the hydrometer is not tempature corrected,
so if you have it set at lets say 1.023 with the temp set at lets say 78 degrees. its accually about 1.025.
theres a calculator on here somewhere, i have the link but its not working..


Registered Member
Individuals who keep reef tanks tend to keep the specific gravity of their tanks close to reef norm .. that about 1.025 or so. People who keep fish only tanks often keep their tanks at lower salinity levels because it cost less (less salt) and less salinity can have a minor benefit to fish.

Swing arm hydrometers have a reputation for being inaccurate. A std glass hydrometer is more accurate and a refractometer is an improvement over most glass hydrometers.


New member
I have noticed that the slightest little bubbles on the swing-arm can through the reading off by a mile, so you definitely have to be very careful.

I do plan to get a refractometer when my budget allows.

Thanks for the input.