Since Specific Gravity is a ratio, it has no units, but it is dependent upon both the temperature of the substance and the temperature of the water reference.ĭensity and Specific Gravity are never the same, because Density has units and Specific Gravity is dimensionless, but they are numerically equal when three conditions are met: (1) Density is measured in grams per cubic centimeter, grams per milliliter, or kilograms per liter (2) Density and Specific Gravity are measured at the same temperature and (3) the Specific Gravity is referenced to water at 4☌, where its Density is very close to 1 gram per cubic centimeter. Specific Gravity, on the other hand, is defined as the weight of a sample, at a given temperature, divided by the weight of the same volume of water, at the same temperature or a different specified temperature. It is usually measured in grams per cubic centimeter, grams per milliliter, pounds per cubic foot or pounds per gallon, and is somewhat dependent on temperature and, to a lesser extent, pressure. Density is defined as the ratio of the mass (weight) to volume of a substance.
Water movement of any kind makes it difficult to read correctly.Density and Specific Gravity are related concepts that are often confused. **Pro tip: Do not measure directly in your display tank. To avoid any distortion of future measurements, rinse the measuring cylinder well with fresh tap or reverse osmosis water to remove salt residues after each use.Now read the specific gravity on the blue part of the scale of the hydrometer at the level of the water's surface - DO NOT reference the edges of the meniscus creeping higher above the waterline.Gently place the hydrometer into the water until it floats freely.The hydrometer should be dry and clean.Fill the measuring container with saltwater (water temperature = 25 ° C / 77 ☏).
#Hydrometer temperature conversion how to
How To Use The Tropic Marin Floating Hydrometer If your water is really cold (or hot), you need to adjust the water temperature accordingly before taking a measurement but you can also just calculate using the appropriate conversion factor or better yet, an online calculator. You can get away with a usable measurement as long as the sample is within 4-5 degrees of 77☏. This hydrometer is calibrated at 77☏ meaning the water your measuring needs to be heated to 77☏ (or as close as possible) for an accurate measurement. Get Some valuable tips for using Tropic Marin Salt Mix and learn how to choose the right salt for your reef tank.īeing made of glass, the unit is fragile so breakage is a small risk and it does not have ATC - automatic temperature compensation so the temperature of the saltwater your measuring matters. It never requires additional calibration checks and will continue providing accurate measurements for many years when cared for properly. Tropic Marin's version is coveted for being highly reliable because every single one is made of hand-blown glass and calibrated before packaging.
Furthermore, traditional analog refractometers also need a substantial natural light source to take a measurement.įloating glass thermometers have been around for decades and will provide users with quick and accurate specific gravity readings almost instantaneously. The downside is they can fall out of calibration easily, requiring frequent checks and re-calibration. They work great, are fairly simple to use, and can generally provide both specific gravity and salinity measurements. Refractometers are hands down the most widely used method of measuring specific gravity. The Tropic Marin Floating Hydrometer is most certainly one of those scenarios. Technology like this certainly has its place in the hobby but sometimes, there is just is no reason to change what is not broken. Digital testing equipment that produces accurate results and reduces the risk of human error during the testing procedure saves us both precious time and money. As modern hobbyists, we sure have it easy compared to days past.
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