Bradsreeeftank
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Title has qustion
Does temp of water affect salinity reading?
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Yes. If you have a device that is calibrated via specific temperature.
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Bradsreeeftank
Well-Known Member
zWIll it affect a hydrometer or refractometer? Thanks
Yes it does affect hydrometers since they are not temperature corrected. Most refractometers are ATC.
Bradsreeeftank
Well-Known Member
Ok thank you!
+1...
ATC = Automatic Temperature Compensating in case you were curious.
Do you use a refractometer, floating hydrometer, or the swinging arm hydrometer?
Bradsreeeftank
Well-Known Member
swinging arm for now
Swinging arm is a hydrometer and doesn't measure salinity, but rather specific gravity.
SG is a ratio of the density of your saltwater to "pure" water. For our purposes, it's the density of saltwater to RODI water.
The density of water affects the buoyancy of objects. The density of the swinging arm is known by the manufacturer, so depending on where the arm is pointing, your hydrometer points to the density of the water.
These are typically inaccurate due to multiple factors - including temperature. Hydrometers are calibrated to a specific temperature because water expands as it heats up and thus, the density changes. If you aren't measuring your water at the temperature your hydrometer was calibrated to, then you aren't getting accurate (or helpful) information.
Salinity is the measure of dissolved salt in your water. For our hobbies' purposes it's measured in parts per thousand. 35ppt is pretty standard for reef tanks - but to give you an idea of how SG changes with temperature
If you have 1 gallon of saltwater with a salinity of 35ppt - at 72F the SG is about 1.026, at 77F the SG is about 1.025, at 81F it's 1.024. Same salinity, different SG.
This is the reason you typically see the ranges of SG given for recommended params for livestock (1.023-1.025, for example).
If we are to assume that your reef tank is being kept within an acceptable temperature range for your livestock, then your concern is to keep your salinity level stable and consistent. The SG measurement at that point kind of becomes irrelevant.
Also, it's much easier to measure salt to mix if you have a scale that measures grams
Mix 35g per 1000g of water. 1 gallon is 4404g.
An adequate refractometer will run you $35-40 and will make your water measuring much easier and more accurate.
(Amazon.com: Salinity Refractometer, Aquarium & Seawater - Dual Scale (1.0 to 1.070 S.G.) by Agriculture Solutions: Pet Supplies)
If you get a refractometer, I would recommend calibrating it against your RODI or Saltwater, and then having your LFS check your meter with their water to confirm.
SG is a ratio of the density of your saltwater to "pure" water. For our purposes, it's the density of saltwater to RODI water.
The density of water affects the buoyancy of objects. The density of the swinging arm is known by the manufacturer, so depending on where the arm is pointing, your hydrometer points to the density of the water.
These are typically inaccurate due to multiple factors - including temperature. Hydrometers are calibrated to a specific temperature because water expands as it heats up and thus, the density changes. If you aren't measuring your water at the temperature your hydrometer was calibrated to, then you aren't getting accurate (or helpful) information.
Salinity is the measure of dissolved salt in your water. For our hobbies' purposes it's measured in parts per thousand. 35ppt is pretty standard for reef tanks - but to give you an idea of how SG changes with temperature
If you have 1 gallon of saltwater with a salinity of 35ppt - at 72F the SG is about 1.026, at 77F the SG is about 1.025, at 81F it's 1.024. Same salinity, different SG.
This is the reason you typically see the ranges of SG given for recommended params for livestock (1.023-1.025, for example).
If we are to assume that your reef tank is being kept within an acceptable temperature range for your livestock, then your concern is to keep your salinity level stable and consistent. The SG measurement at that point kind of becomes irrelevant.
Also, it's much easier to measure salt to mix if you have a scale that measures grams
Mix 35g per 1000g of water. 1 gallon is 4404g.
An adequate refractometer will run you $35-40 and will make your water measuring much easier and more accurate.
(Amazon.com: Salinity Refractometer, Aquarium & Seawater - Dual Scale (1.0 to 1.070 S.G.) by Agriculture Solutions: Pet Supplies)
If you get a refractometer, I would recommend calibrating it against your RODI or Saltwater, and then having your LFS check your meter with their water to confirm.
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