When using a conventional ‘saltwater’ or ‘brine’ refractometer for the reef aquarium we must therefore look to achieve a reading of 36.8ppt if our intended salinity is 35ppt or 37.3ppt if our intended salinity is 35.5ppt as quoted for the H2Ocean salt. Normally the range is 10-35C and is achieved by a small bimetallic strip in the body of the refractometer which responds to the change and moves the graduated scale accordingly. salinity salinity is a blend of salts specifically formulated for the reef aquarium that contains all essential major, minor, and trace components found in natural reef waters, but … Digital Salinity Tester for Salt Water - Aquarium Salinity Meter with ATC, IP67 Waterproof, 0-200 PPT Large Range Multi-Parameter Tester for Seawater, Fish Tank, Hydroponics 4.3 out of … This means that it was originally calibrated with both pure water and sample water temperatures set at 20C and so in order to recalibrate the instrument properly you must use the same temperature for your calibration sample. Remember that even if your aquarium is running at say 27C (80.6F), the refractometer will always read as if it were at 20C. Why are we talking about Salinity now instead of S.G. and what is the difference?? The generally accepted standard salinity for natural seawater, (NSW), is 35ppt. And, as busy as we sometimes are, we don’t even realize our parameters are out of whack until it’s too late. All readings are based upon  mixing salt water to a concentration of 35 ppt or a specific gravity of 1.026. But sea water is not just “salty”; it contains a precise mix of trace elements, all of which should be present in an artificial replacement. Safe Water to Use for Mixing Saltwater Making saltwater for your aquarium Note that some sources recommend that the "Maximum Safe Salinity of Make-Up Water Note that some sources recommend that the "Maximum Safe Salinity of … This of course can be quantified quite easily, however as the density of a liquid is calculated as the weight of a unit volume of that liquid and because liquids expand with temperature, then the volume that we measure and subsequently the weight of that volume will also change. I don't think that the salinity of a marine aquarium must be any one particular value withing a range of 28 to 36 ppt, (1.020 to 1.026). Using a commercial salt mix, you create water for the aquarium that is in many ways superior to natural sea water, with buffers to help maintain the proper pH, as well as additional calcium and other trace elements to maintain corals, clams and other reef invertebrates. NOT QUITE TRUE - At a simple level this is correct however as you get further into the subject you will find that the S.G. reading that you obtain may be more specific to the equipment you have chosen to use to measure it rather than to the actual salt concentration in your tank. Many aquarists prefer RODI units that combine reverse osmosis (RO) and deionization (DI) to remove impurities and undesirable compounds from tap water. Title Saltwater Aquarium Water Parameters Guidelines Author Hanna Instruments Subject Saltwater Aquarium Water Parameters chart that is a general guideline of acceptable water parameter ranges for saltwater aquariums. Those with greater understanding may go into further detail and tell you that the S.G. is 1.025 at 25C, but where does this figure come from, and is it the best way to measure or express the amount of salt in your aquarium, is it even the correct level to be running at? Section #1 is a simple overview of specific gravity and how to select then adjust for the best SG in the marine aquarium. Slowly add salt to the water, rather than putting the salt in first and then filling the bucket to prevent precipitation and clumping. Salinity is the measure of the concentration of dissolved salts (ions) in the water, often given in ppt – parts per thousand. Aquarium Abbreviation Dictionary Image Gallery 30 chevron_right aquariums chevron_right diving chevron_right hawaii Salinity Conversion (Specific Gravity / PPT) Specific Gravity Parts Per Thousand Reading: <-- Convert <-- . If as a consequence of measurement or calibration technique you do end up with a low salt concentration in your tank or salt mix, a salinity of only 33ppt for example. The Tropic Marin High Precision Hydrometer for example quotes 25C/25C on the instructions which means that it is calibrated using the density of both the sea water and pure water at 25C. Although sodium chloride is the main constituent of NSW, it varies in refractive index due to the lack of other ions such as calcium and magnesium which are found in seawater. This calculator converts between various units of salinity. Swing arm hydrometers normally show a salinity scale and an S.G. scale but calibration temperatures may vary from one manufacturer to another. Further investigation brought to light a number of anomalies and misunderstandings regarding the whole issue of S.G. and S.G. measurement and has prompted me to write this article which tries to illustrate some potential problems when using specific gravity as a unit of measurement without a full understanding of what is actually being measured. If you go back to the original definition of specific gravity you will see that we calculate the S.G. as the density of a sample of SEAWATER at a specific temperature divided by the density of PURE WATER at a specific temperature. Ideally you’ll be looking for a salinity of 34 to 36 ppt or a specific gravity from 1.021 to 1.026. General aquarium salt, which is simply sodium chloride and other specialized mixes such as cichlid salt are not suitable for a marine or reef set-up as they do not include the ions necessary for oceanic organisms to thrive. With Aquarium calculator; Convert salinity between relative specific gravity (sg), parts-per-thousand (ppt), and units of conductivity (mS/cm). With this instrument you should therefore be looking to measure an S.G. of 1.0264 and not 1.025 for the same 35ppt water sample. We can see from the above that by using a pure water temperature standard of 20C that the S.G. of 35ppt NSW does in fact approximate to 1.025 which is perhaps where the figure comes from however you can also see the potential range that becomes available if another standard temperature is used. Handheld salinity refractometers (analog) This is the cheapest and most commonly used aquarium refractometer. Salinity, in plain terms, is the concentration of salt in aquarium water. Saltwater aquarium salinity is usually kept between 1.020-1.028sg. Should I Remember that the most important thing for your aquarium is consistency and stability. This can now be used to measure the sample salinity accurately but only whilst the refractometer is still at 20C. If you have live plants in your aquarium, avoid using too much salt. What they should really do is to add more ‘salt’ to raise the salinity, and bring ‘all’ of the levels up together. Replenish evaporated water with clean fresh water, as salts remain when water evaporates. Making saltwater for your aquarium begins with finding a pure water supply. 4.2. With our new found understanding of the relationship between salinity and specific gravity we can expect that the 35.5ppt standard can correctly equate to an S.G. anywhere between 1.0247 and 1.0267 depending on the hydrometer used. So with your refractometer at 20C, which is close to normal room temperature, you add a sample of distilled or RO water to the screen and use the adjustment screw to line up the blue marker with the zero salinity mark. As a general guideline, it is best to maintain a salinity of 1.026 (or 35ppt or 53 mS/cm conductivity) and know where your aquarium fish come from to distinguish what their natural salinity level is. 1.025 at 25C. Specific gravity indicates density, while salinity refers to the actual weight of the salt. 20-25 percent of the water should be replaced per month, ideally about 10 percent every other week or as needed according to water chemistry test results. Even each brand of marine salt mix varies from natural seawater’s concentrations of the four major ions (sodium, chloride, sulfate and magnesium), as well as other trace elements. Most freshwater tropical fish live quite comfortably at the temperature of most homes (65 0 to 85 0 F, 18 0 to 30 0 C). If you have an auto temperature compensating model (ATC) you must still calibrate the unit at the calibration temperature of 20C however this version, once correctly set, will auto adjust for environments where the instrument warms or cools away from this temperature. When to Avoid Salt Live plants: If you have live plants in your aquarium, avoid using too much salt. I suspect, rightly or wrongly, that the specific gravity levels that we as hobbyists use in our aquariums may be historical from general oceanographic studies and it is not immediately clear when or where the 1.025 at 25C standard originates from. However, some microorganisms can withstand higher salinity, which is why salt is not a 100% bulletproof solution. Next, choose a salt mix. Some aquarists like to keep fish only aquariums at lower levels (1.017+) to keep salt costs low and to reduce problems with parasites, which don’t survive as well in lower salinity. Salinity is the measure of how much salt is dissolved within a body of water, and keeping it as constant as you can is one of your main jobs with a saltwater aquarium. Salinity is a pure weight per weight measurement and as weight is not influenced by temperature then neither is salinity. There can be issues with these units giving false readings over time due to bubbles or deposits attaching to the swing arm or pivot point which change the buoyancy and therefore the reading obtained. This applies to both the salinity and the relative concentrations of all elements within the salt and so any changes in salinity, salt brand or parameters should be made gradually. Mix your new salt water a day or two in advance. Understand that the S.G. scale is not a constant number across all measuring equipment and reference sources. Aquarium The only limit is what you can imagine. Specific Gravity, or relative density, is expressed as the ratio of the density of seawater relative to the density of the same volume of pure water. PH 7.9-8.4 Temperature 76-80 degrees F Salinity … Top up evaporated loss regularly or fit an auto top up system to reduce swings in salinity to a minimum. Make sure all salt is completely dissolved before testing to ensure accurate readings. Otherwise, I suggest targeting a salinity of 35 ppt (specific gravity = 1.0264; conductivity = 53 mS/cm; refractive index = … how to measure salt level (salinity) in a saltwater aquarium with a refractometer. EXAMPLE: If we calculate the specific gravity for a sample of 35ppt seawater using a standard density temperature of 25C for the seawater sample but vary the density temperature used for the pure water, we can see how this affects the specific gravity result? Add more salt mix to raise the salinity or more fresh water to lower salinity. These new models are easily identified as seawater refractometers on the viewing screen and have been produced to show the correct S.G. of 1.0266 for NSW at a salinity of 35ppt and a sample/pure water density of 20C and a reduced range of salinity from 0 -40 rather than 0 – 100. If the normal calcium level of NSW at 35ppt is 420ppm then at 33ppt salinity this will only be 396ppm and if the aquarist is not aware of his low salinity and adds more calcium to raise the level to 420ppm then they will be putting this particular element out of balance with the rest of the salt whilst ignoring other elements that may be just as important for the proper biological function of the organisms we keep. Salinity can be measured by (a) boiling down a water sample, (b) measuring conductivity by electronic means, and (c) other laboratory methods which are either too complex or too expensive. C). Aquarium Temperatures The temperature of an aquarium is much less important than hobbyists give it credit for. Use a refractometer or hydrometer to measure the salinity and adjust accordingly, you want to match the salinity of your aquarium if you’re performing a water change. Unfortunately there are a number of different temperature standards commonly used in oceanography and so printed tables for PURE WATER density can be quoted at 4C, 60F (15.56C), 20C or 25C depending on their intended application. The main reason that we found for this discrepancy, other than general mixing and test kit errors, was due to low specific gravity, i.e. I like to keep my Salinity right around 1.025 to 1.026 range. Another such family is that of the ancient ganoids, Lepisosteidae. ρs is the density of 35ppt seawater at temperature T, in this case 25C = 1.023343. ρ0 is the density of pure water at a range of commonly used temperature standards (Tx). Most people, if asked, would probably tell you that their reef aquarium is running at an S.G. (Specific Gravity) of 1.025. Follow the manufacturer’s directions on how much mix to use, and check the solution for proper salinity as you add mix. See below for the conversion chart. Refractometers work on the principle that changes in salt concentration affect the refractive index of light and therefore light entering the instrument is deflected by varying amounts onto a graduated scale. In a healthy reef tank with rapidly growing stony corals and tridacnid clams, the demand for calcium, magnesium and other trace elements can be so high that salt mix alone will not provide enough. Salinity is a true measurement of the concentration of salt in the ocean and is calculated as the total weight of ‘dry’ salt dissolved in a total of 1000 weight units of water or parts per thousand, (ppt). This is the temperature at which the hydrometer was designed/calibrated to measure the water sample at –. The majority of refractometers in the hobby are manufactured and calibrated for use with saltwater and not seawater and intended for measuring sodium chloride, (brine) concentrations. Not all salt is created equal in the aquarium world. D-D The Aquarium Solution Ltd - is one of the most well known and respected suppliers of specialist equipment within the hobby for use in salt water and fresh water aquariums.Read More, Visit our page on Facebook for the latest news and events from The Aquarium Solution, Copyright © 2021 by D-D The Aquarium Solution Ltd. All Rights Reserved. Freshwater or saltwater, ensure your water quality with testing. It is not possible to measure the salinity of the ocean or your aquarium directly unless you take a precise weight of seawater and evaporate all of the H20 from it then measure the weight of the residue, (mass solids analysis). Fact Sheet 3.1.3.0 The Clean Water Team Guidance Compendium for Watershed Monitoring and Assessment State Water Resources Control Board FS-3.1.3.0(EC)V2e 4/27/2004 Page 1 Electrical Conductivity/Salinity Fact It is important to know the salinity of your tank and any new seawater you make before topping off. The salinity of the world’s oceans is not constant and varies substantially from one location to the next with concentrations of just 10-15ppt in the Baltic Sea to around 40ppt in the Red Sea. For this reason copper bodied refractometers are better than the lower cost plastic ones as they conduct the ambient temperature changes faster. When using a conventional ‘saltwater’ or ‘brine’ refractometer for the reef aquarium we must therefore look to achieve a reading of 36.8ppt if our intended salinity is 35ppt or 37.3ppt if our intended salinity is 35.5ppt as quoted for the ρ0 (15.56C) = 0.9990166       SG = 1.023343/0.9990166              = 1.02435, ρ0 (20.0C) = 0.998203            SG = 1.023343/0.998203                = 1.02519, ρ0 (25.0C) = 0.997047958     SG = 1.023343/0.997047958         = 1.02637. You may also add calcium, magnesium, alkalinity buffers or other elements after the salt has dissolved. Maybe I have been lucky b/c I have never had any issues what so every with the Apex Salinity probe. The following chart is a comparison guide for Calcium, Alkalinity, and Magnesium  levels in our most popular artificial marine aquarium salt mixes. Some types of displays such as FOWLR (Fish Only With Live Rock) aquariums have a broader range of parameters than a reef aquarium. You should then equally expect that the concentrations of ‘all’ elements will be low as a consequence compared with the target concentrations found in natural seawater. Use an air stone or power head in the water to circulate and aerate the mixture. Aquarium experience shows that many other cichlids will survive high salinity. The following chart is a general guideline of acceptable water parameter ranges for different types of tropical marine aquariums. My reading on Apex salinity probe is 51.5 which roughly equates to 1.025 specific! Whilst this may seem a small difference we should remember that it does have a significant impact on the true concentration of the dissolved elements in our aquariums. Such a system can require almost constant supplementation. SIMPLES - to use the words of a well known Russian meerkat - All we need to do is to ensure that our sample water is at that temperature and the specific gravity will be exactly right. Maintaining consistent salinity in your aquarium is key to the well being of every organism inside it. Many people may have noticed on their hydrometers that there is a temperature quoted on the side, normally in small writing. It’s pretty simple – if the water They are a convenient, fast and easy method of keeping check on the salinity in your aquarium or when mixing up new batches for water changes. With the possible exception of certain invertebrates, marine animals and biological filters do better at Start with a large vessel (large buckets or plastic trash cans work well) of reverse osmosis (RO) or distilled water. More specifically, salinity is a measure of the dissolved sodium ions in the water and it can be measured in parts per thousand (ppt). They are extremely delicate and easy to break and generally only display an S.G. scale which means you need a complete understanding of both the sample calibration temperature required, and the pure water calibration standard used to be able to relate the reading back to a particular salinity. Altering salinity of your tank significantly may also alter alkalinity, calcium, magnesium, and other ions to the point where they will need adjustments, so be sure to have test kits on hand to monitor these levels. Hydrometers – understand the calibration temperature requirements, and take note that S.G. is not a constant number across all measuring equipment and reference sources. This brings us back full circle to the point that the salinity scale which we talked about at the start is perhaps a much better way of expressing the salt concentration of your aquarium as we do not have the same potential for variation however most glass hydrometers do not even show this scale. Salinity and Temperature are two of the most easiest and overlooked tests for ideal water parameters. Salinity is one of the most important parameters to monitor in your aquarium because without salt, you have a Freshwater Aquarium! Learn when and how to use salt in your freshwater aquarium. Through the power of osmosis, aquarium salt is able to eliminate many pathogens and parasites on fish. The more expensive glass hydrometers are very accurate but time consuming to use as they require a clear sided vessel in which to float and for the water to be at the exact calibration temperature. While some of the few existing species have not yet … Refractometers – understand the calibration requirements and apply an offset to measure the true seawater salinity if using a saltwater/brine model. The higher the density or salt content the more cargo the ship can hold without sinking. Simply calibrate the refractometer, add a couple drops of aquarium water to the refractive prism and stare into the All of these readings are for the same sample of 35ppt seawater at the same sample temperature of 25C. Tap water, whether drawn from a well or from a municipal supply, can contain various chemicals or dissolved minerals that can be harmful to your tank. Major problems can arise if they are off but they are some of the most preventable problems. What many people do not understand however is that it is the temperature of the instrument that should be at 20C and not the liquid as the few drops of sample water contains so little heat that it soon equilibrates to the same temperature as the refractometer body. But stop a minute!! There are many water filtration systems available that will produce purified water for use in your aquarium, which may be the safest solution. Unfortunately all of these alternative parameters ‘are’ affected by temperature and so even when measuring salinity, which is not temperature dependant, we must still make an allowance because of the indirect test method. Clean, pure saltwater is crucial to the health and well-being of creatures in your marine aquarium. If the organisms in the aquarium are from brackish environments with lower salinity, or from the Red Sea with higher salinity, selecting something other than S=35 may make good sense. The result of these additional elements is that the refractive index changes so that a 35ppt seawater solution approximates to the same refractive index as that of 36.8ppt brine. To measure the amount of salt in our aquarium by way of an S.G. reading, we must therefore understand which pure water temperature standard and which sample water temperature standard was originally used when calibrating the hydrometer or refractometer which is not constant between all equipment and manufacturers. Section #2 offers more in depth information as to what specific gravity, salinity … It is with density of the pure water that the problem or potential for error occurs. Water changes should be performed regularly on your marine aquarium. 1. Normal seawater is about 35 ppt salts. The main ions are sodium (Na), chloride (Cl), magnesium (Mg), and sulfate (S04), forming the salts (NaCl and MgS04). This calculator creates a water-change schedule that can be followed to reach a target salinity in an aquarium. The main drive behind this article was to enlighten people on the potential variation between different specific gravity measurements, and to show individuals why they often find varying concentrations of major elements such as calcium and magnesium in their tanks compared with what they ‘expect to find’ or have been ‘told that they should find’ in their salt mix. We discussed earlier that as aquarists we do not measure salinity or specific gravity directly and instead measure another parameter which has a relationship with the salt concentration such as refractive index in the case of a refractometer, buoyancy in the case of a hydrometer and conductivity if measured electrically. These devices provide values for specific gravity or salinity. Of course once we gave people levels to test against we received a steady stream of emails and threads from individuals who were measuring readings outside these guaranteed parameters. Salinity 1.023 – 1.028 SG Alkalinity 9-12 dkh Calcium 400-450 ppm Magnesium 1200-1440 Phosphate 0-.05 Nitrate 0-10ppm Nitrite 0 Ammonia ZERO! These charts were used to allow a simple way of calculating the changes in seawater density across the various oceans which affects how much cargo a ship can carry on a journey from one destination to another. There are various glass and plastic hydrometers available to aquarists on the market which work on the principle of buoyancy, where the denser the liquid in which it is immersed, the higher it will float. Obviously this is not a convenient technique for the average hobbyist, so we use other methods to determine the salinity indirectly. not enough salt in their water. To use a refractometer properly we must first understand the correct calibration procedure. Otherwise, I suggest targeting a salinity of S=35 (specific gravity = 1.0264; conductivity = 53 mS/cm). Ideally you’ll be looking for a salinity of 34 to 36 ppt or a specific gravity from 1.021 to 1.026. D-D quote figures on the concentrations of the main elements in our H2Ocean salt at 35.5ppt which is an average of the readings found in the coral seas. Seawater is composed of many different ions (salts) in different concentrations. There are a number of tools used to measure salinity, but a simple hydrometer or refractometer will give you accurate results. Some electronic probes has automatic temperature correct, if this is the case the display will show the conductivity at 77°F (25°C). Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation Measure salt water or salinity of water, ideal for aquariums and marine monitoring. Once mixed, artificial seawater can be stored for as long as needed without continuous stirring, and having a small reservoir of mixed saltwater ready to use provides extra insurance in case of emergency or unforeseen accidents. salt level in aquarium : how to measure salinity : using a refractometer. Never mix the salt in the aquarium. When we brought out the D-D H2Ocean Pro+ reef salt a few years ago, we were adamant that we wanted to print the exact levels and tolerances for the main important elements that we would expect to find in our salt on every bucket; information that should be readily available to allow an informed choice for every good reef salt. If the aquarium's organisms are from brackish environments with lower salinity, or from the Red Sea with higher salinity, selecting something other than 35 ppt may make good sense. We should always therefore qualify the S.G. by quoting it at a specific measured temperature, e.g. True seawater refractometers have never really existed in the hobby at an affordable price until now but as part of the development of our salt and salt related products, D-D have brought out a new model of refractometer which is specifically calibrated to the salinity of NSW thus removing the requirement to apply an offset to obtain the true reading for your aquarium. These devices provide values for specific gravity or salinity. The cheaper plastic swing arm hydrometers are easy to use and robust but are not always intended to give an absolutely accurate reading and not normally used by more experienced reef keepers housing delicate and expensive stock. Each temperature standard will result in a different pure water density figure which will give a different S.G. when we use that density in our calculation. Concentrations are based upon published manufacturers product literature. Salinity is often tested daily, particularly anytime saltwater is being made, an aquarium is being topped off with freshwater when performing water changes. And remember, replenishing or topping off the tank with fresh water does not qualify as a water change, as accumulated waste materials are not removed.