Checking Salinity

fishgirljockey · Jan 4, 2023

Where has this been my whole life?? Has anyone used or have this? When I saw it at the store, I thought… SHUT UP AND TAKE MY MONEY!! You place it in the tank wherever you like. I have it on the left side of the glass so you don’t see it. All you do is glance over and it shows you where the salinity is. Saves you from having to either put your hands in the tank or go through using the refractor…not that it’s difficult to do or takes a lot of time but you get what I mean. It’s extremely convenient! I did however still check it a second way until I trusted it. I definitely trust this tool. Its been extremely accurate!! It does take a day or less to work. When you first put it in, it will go all the way to the top. Just leave it and wait. The next day is when it started working. Great tool and highly highly recommend! I got mine from Petco for $14.99

MarineandReef Jaron · Jan 4, 2023

I have used these but stopped when I got tired of the suction cups un-sucking, air bubbles driving the arm up, and algae driving the arm down and clouding the view. They might work very well in a mixing station if you could retrofit a magnet mount.

nuxx · Jan 4, 2023

MarineandReef Jaron said:
I have used these but stopped when I got tired of the suction cups un-sucking, air bubbles driving the arm up, and algae driving the arm down and clouding the view. They might work very well in a mixing station if you could retrofit a magnet mount.

LOL yeah, something that would work well when new and not dirty

MarineandReef Jaron · Jan 4, 2023

I will say that I have been thinking of redoing my mixing station switching from brutes to 2 55-gallon tanks on one of those double stands. I was thinking of getting one of the Hanna Marine Monitors but maybe I should just get a stick on thermometer, an internal hydrometer, and a SeaChem pH badge.

Randy Holmes-Farley · Jan 4, 2023

Swing arm hydrometers have a checkered reputation.

I tested several and found this result:

Chemistry and the Aquarium: Specific Gravity: Oh How Complicated!

This month, Randy explains and reviews specific gravity.

reefs.com

So how do these hydrometers measure up? In my tank the water was measured to be S=35 ± 0.5 by conductivity. Using the Deep Six swing arm hydrometer I got readings of S=32.5 ± 0.5 at 81 °F and S=32 ± 0.5 at 68 °F. Using the SeaTest I got S=34.5 ± 0.5 at 81 °F and S=34 ± 0.5 at 68 °F.

For the standard type Tropic Marin hydrometer, I got a 77 °F/77 °F specific gravity of about 1.0265 ± 0.0003 (Figure 4), which compares well to the expected value of 1.0264.