Salinity @ 1.027?!

ilove2ride

ilove2ride

Member
I was just looking at one of my books, and it says that salt becomes less dense with temp. So I use my deep six hydrometer and it says 1.0245. I thought that this was already supposed to be used at nomral temperature.... my tank is 82. THe chart said that the SG would be at 1.027 with this temperature.
The LFS guy said my water was at 1.025.
So basically my question is, after you test with a hydrometer, do you have to look up the reading somewhere else...
:confused:
Thanks.
 
jacksonpt

jacksonpt

Active Member
From what I've heard, most hydrometers are "calibrated" for a certain tempertaure water, i.e. they read accurately at some specified temerature. If your water temp is significantly different from the hydrometer's specified temp, then you'd have to adjust accordingly. Check your hydrometer's packaging or instructions (if it came with any) for info.
 
bang guy

bang guy

Moderator
Most swing-arm type hydrometers for aquarium use are self calibrating within a reasonable temperature. Just let it sit for a minute for the swing arm to warm up. It's not going to be perfectly accurate but close enough.
On another note... swing-arm type hydrometers are notoriously inaccurate. I suggest you check them with a freshly calibrated refractometer every 6 months.... or just get the refractometer ;)
On a third note... Specific Gravity is not important to reef animals at all. It is a tool available to us to get an approximation of the Salinity. The Salinity is vitally important to reef animals.
 
captgut

captgut

New Member

Originally posted by jwtrojan44
A refractometer is a very good investment in this hobby. A nice one can be had for around $70.00 or so in a well stocked lfs. As stated, the swing arms are accurate within their comfort zone, but in the event you need to be "right on", such as when treating for disease (hyposalinity), you can't be messing around. My swing arm measures three points higher than my refractometer. For the price of a couple corals or a few fish, you can have a precision instrument that takes a lot of guess work away.
is this correct, if my tank is at 80 and i use a hydrometer i get a reading that must be adusted but if i put a couple of drops on the
refractometer i get a correct reading.
thanks
 
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