{"title":"Refractometers \u0026 Hydrometers","description":"\u003cspan data-mce-fragment=\"1\"\u003eRefractometer and hydrometers for simple and accurate measurement of salinity\u003c\/span\u003e","products":[{"product_id":"fluval-sea-hydrometer","title":"Fluval SEA Hydrometer","description":"\u003cp\u003eFluval Sea Hydrometer provides an accurate and convenient method of measuring specific gravity and salt level in marine aquariums. Regular testing is strongly recommended as stable salinity levels are essential for the health of marine fish and invertebrates. \n\u003cbr\u003eCompact and easy to use, the hydrometer can be permanently installed inside the tank for continuous readings. Its slim, low-profile design camouflages well inside the tank and will not diminish the aesthetics of the aquarium. It can also be used as a portable device, allowing you to take samples simply by submerging it in the water. It features large, easy-to-read markings with ideal salinity range clearly marked in green for clarity\u003c\/p\u003e","brand":"Fluval","offers":[{"title":"Default Title","offer_id":40196909662343,"sku":"14356","price":7.54,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/fluval-sea-hydrometer-147887.jpg?v=1731256519"},{"product_id":"fauna-marin-salinity-reference-35-ppt-100ml","title":"Fauna Marin Salinity Reference 35 ppt - 100ml","description":"\u003cp\u003eFauna Marin Salinity Reference 35 ppt -  to test your Fauna Marin Salinity Manager is measuring correctly. \u003c\/p\u003e","brand":"Fauna Marin","offers":[{"title":"Default Title","offer_id":40200342208647,"sku":"FM066","price":5.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/fauna-marin-salinity-reference-35-ppt-100ml-524145.jpg?v=1731256418"},{"product_id":"xodis-digital-salinity-meter","title":"Xodis Digital Salinity Meter","description":"Digital salinity meter, measure salinity-SG and PT, Temp, TDS\u003cbr\u003e\u003cbr\u003e\u003cu\u003eFeatures\u003cbr\u003e\u003c\/u\u003e\u003cbr\u003eEasy to use\u003cbr\u003eLarge colour LCD dislay\u003cbr\u003eHigh resolution readings\u003cbr\u003ePrecision measurement\u003cbr\u003eCalibration mode\u003cbr\u003eAutomatic temperature compensation\u003cbr\u003eExclusive 3rd Gen Software \u003cu\u003e\u003cbr\u003e\u003c\/u\u003e","brand":"Xodis","offers":[{"title":"Default Title","offer_id":40200346796167,"sku":"25167","price":89.99,"currency_code":"GBP","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/xodis-digital-salinity-meter-754199.jpg?v=1731257674"},{"product_id":"hanna-waterproof-salinity-tester","title":"Hanna Waterproof Salinity Tester","description":"The new HI-98319 waterproof salinity and temperature tester is perfect for any saltwater aquarium. A more accurate alternative to refractometers, this tester uses conductivity to determine salinity levels of natural and artificial seawater. Ideal for testing salinity in salt water aquariums, it is quick and easy to use and provides digital readout of both salinity and temperature.\u003cbr\u003e\u003cbr\u003eSalinity results are displayed in either parts per thousand (ppt), Practical Salinity Units (PSU), or Specific Gravity (SG).\u003cbr\u003e\u003cspan\u003e\u003cbr\u003eThe salinity tester is supplied complete with batteries and solutions allowing you to start measuring right away. Also displays temperature.\u003cbr\u003e\u003cbr\u003e\u003c\/span\u003eThis pocket sized meter is waterproof and perfect for the measurement of salinity aquariums using conductivity to determine the salinity level of your water.\u003cbr\u003e\u003cspan\u003e\u003cbr\u003eSalinity should be checked regularly in aquariums. As Oceans are very stable environments, where there is not a lot of day to day change in the water parameters, fish can respond negatively to even small changes in salinity.\u003cbr\u003e\u003cbr\u003e\u003c\/span\u003e\u003cbr\u003eEach meter is supplied with:\u003cbr\u003e\u003cbr\u003eCR2032 battery (installed)\u003cbr\u003eStorage\/protection shield\u003cbr\u003eInstruction manual\u003cbr\u003eQuality certificate\u003cbr\u003e35.00 ppt calibration standard sachet (x 4)\u003cbr\u003e\u003cbr\u003eTo obtain the highest accuracy for measurements, it is important to follow these guidelines:\u003cbr\u003e\u003cbr\u003e\u003cli\u003eCalibration is only as good as the solution being used. Fresh solution should be used for each calibration\u003c\/li\u003e\u003cli\u003eThe probe should be rinsed with purified water each time before placing in calibration solution or sample to be tested\u003c\/li\u003e\u003cli\u003eRecommended solution: HI-70024P Calibration Solution 35.00ppt, 25 x 20ml sachets\u003c\/li\u003e\u003cbr\u003e\u003cdiv\u003eBattery Replacement\u003cbr\u003e\u003cbr\u003e\n\u003c\/div\u003eThe meter features a low battery indicator. When the battery is running low, the battery indicator will blink on the LCD. Simply change the CR2032 Li-ion battery by removing the battery cover located on the back of the meter.","brand":"Hanna Instruments","offers":[{"title":"Default Title","offer_id":40200348369031,"sku":"HI-98319","price":89.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/hanna-waterproof-salinity-tester-559049.jpg?v=1731256514"},{"product_id":"red-sea-seawater-refractometer","title":"Red Sea Seawater Refractometer","description":"Red Sea’s Seawater Refractometer offers exceptional accuracy, for measuring the absolute salinity of seawater at a temperature of 25oC\/77 0F. Most refractometers used within the aquarium hobby are not specifically designed for reef aquariums and use an algorithm for the measurement of brine (NaCl – rather than seawater) and at a temperature of 15oC\/59 0F rather than 25oC\/77 0F. Thus, a measurement deviation of up to 1.5ppt is possible, which can have a significant adverse effect on coral growth and coloration. \u003cbr\u003e\u003cspan\u003e\u003cbr\u003eMain features of Red Sea’s Seawater Refractometer include:\u003cbr\u003e- Directly reads the absolute salinity of seawater at 25°C\/77 0F ( No need for seawater or temperature compensation factors)\u003cbr\u003e- Specifically designed for the ionic content of seawater (NSW) for more accurate salinity measurement (industry standard refractometers are calibrated for salt brine ).\u003cbr\u003e- Calibrated for seawater (NSW) at 25oC\/77oF, the normal temperature range for reef aquariums (most standard refractometers are calibrated at 15oC\/59oF ).\u003cbr\u003e- Easier to read, higher resolution display, focussed to the relevant range for reef aquariums of up to 40ppt\u003cbr\u003e- Includes Integrated Automatic Temperature Compensation (ATC) for accurate measurement at standard ambient temperature.\u003c\/span\u003e \u003cbr\u003e\u003cbr\u003eRed Sea’s Refractometer display The PPT scale on Red Sea’s Seawater refractometer is calculated using an algorithm for seawater and therefore will give a reading of the Absolute Salinity of seawater. The PPT scale on regular salinity refractometers are calculated using an algorithm for Brine. Using a Brine refractometer for Seawater will give an error of approximately 1.5ppt in the salinity reading. About Salinity Salinity is a general term describing the concentration of salt in water. However, solutions of different type of salts have different refractive indexes. Brine is a solution of Sodium Chloride (table salt) that contains 2 chemical elements. Seawater contains approximately 70 chemical elements that include Calcium, Magnesium, Potassium etc. in addition to the Sodium Chloride. Seawater and Brine of the same salinity (i.e. the same weight of salt\/liter) have different refractive indexes and will give different salinity readings if measured on the same refractometer. Refraction \u0026amp; refractive index All transparent materials such as liquids refract (distort) light. All transparent materials refract light differently and have what is called a “refractive index” which means how much a particular material distorts light. Different concentrations of the same liquid have different refractive indexes. The scale of a refractometer is calculated by using a mathematical algorithm that relates the measured refraction to its concentration for a specific liquid. Refractive index and temperature The refractive index of liquids change with temperature and therefore has a major effect on measuring salinity with a refractometer. The algorithm for defining the PPT (and S.G.) scale for a refractometer is calculated for a specific temperature. PPT readings from refractometers that are not calibrated for reef aquariums (i.e. 25oC) need to be adjusted according to a conversion table to give the actual PPT at the aquarium temperature. This is often a cause for misinterpretation of refractometer readings. For example, using a seawater refractometer calibrated at 20oC will give a PPT reading that is approximately 1-1.5ppt lower than the absolute salinity of the same water sample at the normal aquarium temperature of 25oC. Therefore, Red Sea’s Seawater Refractometer calibrated at 25°C\/77 0F directly reads the absolute salinity of seawater with no need for temperature compensation factor) ATC – Automatic temperature compensation Temperature is probably the biggest cause of wrong readings with a refractometer. Calibration and testing of water samples should be done after the refractometer and water sample have equalized at the correct temperature. Automatic temperature compensation (ATC) compensates for a few degrees of difference between the ambient temperature and the calibrated temperature of the refractometer. Larger temperature variations will give an error of approximately 1.0ppt in the salinity reading. ATC does not adjust the PPT reading of a refractometer to the temperature of the aquarium","brand":"Red Sea","offers":[{"title":"Default Title","offer_id":40200357478535,"sku":"R12018","price":52.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/red-sea-seawater-refractometer-568775.jpg?v=1731257230"},{"product_id":"tmc-v2-refractometer","title":"TMC V2 Refractometer","description":"The V2 Refractometer is designed for testing the concentration of salt water and brine and is used for quality control in the marine industry and in research and clinical laboratories. The V2 Refractometer's dual scale provides a direct reading of the specific gravity and parts per thousand (ppt) of salt in water.\u003cbr\u003e\u003cbr\u003eProduct Information:\u003cbr\u003e\u003cspan\u003e• High resolution, dual scale - SG and PPT\u003cbr\u003e• Simple focus adjustment\u003cbr\u003e• Wipe-clean lens\u003cbr\u003e• Easy to calibrate - screwdriver supplied\u003cbr\u003e• Simple water application - pipette supplied\u003cbr\u003e• Automatic temperature compensation\u003c\/span\u003e\u003cbr\u003e\n\n\u003cspan\u003e\n\n\n\n\n\n\u003c\/span\u003e","brand":"TMC","offers":[{"title":"Default Title","offer_id":40200363114631,"sku":"9501","price":32.49,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/tmc-v2-refractometer-337217.jpg?v=1731257502"},{"product_id":"d-and-d-portable-refractometer","title":"D and D Portable Refractometer","description":"\u003cdiv\u003e\u003cb\u003eWhat’s different between our NEW refractometer and others you might ask?\u003c\/b\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cb\u003e \u003c\/b\u003e\u003c\/div\u003e\u003cdiv\u003eAlmost all, if not all, of the refractometers currently available to the aquarium hobby are designed for measuring saltwater (sodium chloride or brine solution) and not true ‘\u003cb\u003eseawater’. \u003c\/b\u003eAlthough seawater is mostly sodium chloride it also contains other elements such as magnesium and calcium that change the refractive index slightly and will give a slightly different result.\u003c\/div\u003e\u003cdiv\u003e \u003c\/div\u003e\u003cdiv\u003eThe most common symptom of this difference in refractive index can be seen when mixing up salt as per salt manufacturer’s instructions and achieving a solution strength where it appears, through testing, that the levels of elements are lower than stated by the manufacturer. In actual fact all of the levels are low as the salinity is not as high as the aquarist believes – we have all seen low Ca or Mg for a given SG with almost all brands of salt.\u003cbr\u003e\n\u003c\/div\u003e\u003cdiv\u003e \u003c\/div\u003e\u003cdiv\u003eIt turns out that a 35ppt solution of true seawater has the same refractive index as a 36.5ppt solution of brine and so when using a brine\/salt refractometer the salinity is likely to be low by 1.5ppt. This can be allowed for by the aquarist but only if they are aware of the difference.\u003c\/div\u003e\u003cdiv\u003e \u003c\/div\u003eAfter extensive development, D-D’s new refractometer addresses this issue, giving true salinity results when correctly calibrated and greater accuracy than previously attainable.\u003cbr\u003e\u003cbr\u003e\u003cdiv\u003e\u003cb\u003e\u003cu\u003eFeatures: \u003c\/u\u003e\u003c\/b\u003e\u003c\/div\u003e\u003cdiv\u003e \u003cbr\u003e\u003cspan\u003eTrue calibration for Seawater measurement. \u003cbr\u003e\u003c\/span\u003e\u003cspan\u003e\u003cbr\u003eA New finer scale running from 20-40ppt salinity (SG 1.015 - 1.030) \u003cbr\u003e\u003c\/span\u003e\u003cspan\u003e\u003cbr\u003e20\/20 calibration at room temperature for more consistency and accuracy in everyday use. \u003cbr\u003e\u003c\/span\u003e\u003cbr\u003eFull ATC (\u003ci\u003eauto temperature compensation\u003c\/i\u003e) ranging from 5 to 30 deg C\u003c\/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e","brand":"D-D","offers":[{"title":"Default Title","offer_id":40200363901063,"sku":"R62302","price":42.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/d-and-d-portable-refractometer-920286.jpg?v=1731256056"},{"product_id":"25-pack-hanna-35ppt-salinity-calibration-solution","title":"(25 PACK) Hanna 35ppt Salinity Calibration Solution","description":"\u003cspan\u003eHI-70024P is a premium quality 35.00 ppt marine salinity solution standardised with a conductivity meter that has been calibrated with potassium chloride NIST 2202 SRM (Standard Reference Material) in deionised water for analytical use in accordance with ISO 3696\/BS3978. Additional equipment used in preparation of the solutions include certified weight-checked balances, Class A glassware and certified thermometers.\u003cbr\u003e\u003cbr\u003e\u003c\/span\u003e\u003cspan\u003eHanna calibration solutions have a lot number and expiry date clearly marked on the label. All sachets are air tight to ensure the quality of the solution.\u003cbr\u003e\u003c\/span\u003e\u003cbr\u003e\u003cdiv\u003eIdeal for use with the Hanna Salinity tester\u003c\/div\u003e","brand":"Hanna Instruments","offers":[{"title":"Default Title","offer_id":40508779331719,"sku":"HI-70024","price":46.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/25-pack-hanna-35ppt-salinity-calibration-solution-890149.jpg?v=1731255768"},{"product_id":"single-hanna-35ppt-salinity-calibration-solution","title":"(SINGLE) Hanna 35ppt Salinity Calibration Solution","description":"\u003cspan\u003eHI-70024P is a premium quality 35.00 ppt marine salinity solution standardised with a conductivity meter that has been calibrated with potassium chloride NIST 2202 SRM (Standard Reference Material) in deionised water for analytical use in accordance with ISO 3696\/BS3978. Additional equipment used in preparation of the solutions include certified weight-checked balances, Class A glassware and certified thermometers.\u003cbr\u003e\u003cbr\u003e\u003c\/span\u003e\u003cspan\u003eHanna calibration solutions have a lot number and expiry date clearly marked on the label. All sachets are air tight to ensure the quality of the solution.\u003cbr\u003e\u003c\/span\u003e\u003cbr\u003e\u003cdiv\u003eIdeal for use with the Hanna Salinity tester\u003c\/div\u003e","brand":"Hanna Instruments","offers":[{"title":"Default Title","offer_id":40508779364487,"sku":"HI-70024","price":2.31,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/single-hanna-35ppt-salinity-calibration-solution-509273.jpg?v=1731255768"},{"product_id":"fauna-marin-cleaning-solution-100ml","title":"Fauna Marin Cleaning Solution 100ml","description":"\u003cspan\u003eThis cleaning solution is for the Fauna Marin Salinity Manager to ensure it is clean to give the most accurate reading. \u003c\/span\u003e","brand":"Fauna Marin","offers":[{"title":"Default Title","offer_id":40508799647879,"sku":"FM068","price":5.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/fauna-marin-cleaning-solution-100ml-725010.jpg?v=1731256414"},{"product_id":"fauna-marin-multi-reference-100ml","title":"Fauna Marin Multi Reference 100ml","description":"\u003cspan\u003eWith the Fauna Marin Multi-Reference Solution, you can test your test kits under accurate conditions. Our Reference Solution is the first to be based on a saltwater matrix and is quality tested using our ICP-AES testing machine. We use a saltwater matrix that is similar to aquarium water so that all common variables which affect normal water tests are taken into account.\u003cbr\u003e\u003c\/span\u003e\u003cspan\u003e\u003cbr\u003eEach batch is quality controlled and tested in our Seawater Research Laboratory to ensure accurate and reliable solutions, every time.\u003cbr\u003e\u003cbr\u003e\u003c\/span\u003e\u003cdiv\u003eOur 100ml solution is stable and combines all these values into a single solution – the values vary with each batch! Please check your Multi Referenz bottle for the respective values.\u003cbr\u003e\u003cbr\u003e\n\u003c\/div\u003eCalcium – 425 mg\/L\u003cbr\u003eMagnesium – 1,315 mg\/L\u003cbr\u003ePotassium – 375 mg\/L\u003cbr\u003eSalinity – 33.9 ppt (51.6 mS) @ 75°F\u003cbr\u003eAlkalinity – 7 DKH (2.5 meq\/L)\u003cbr\u003eStrontium – 7.1 mg\/L\u003cbr\u003eNitrate – 11.5 mg\/L\u003cbr\u003ePhosphate – 0.05 mg\/L\u003cbr\u003e\u003cbr\u003e\u003cdiv\u003eMulti-Reference Solution is especially useful for\u003c\/div\u003e\u003cul\u003e\n\u003cli\u003eTesting the validity of new test kits\u003c\/li\u003e\n\u003cli\u003eVerifying results after unexpected test results\u003c\/li\u003e\n\u003cli\u003eTesting kits that were stored for a long time\u003c\/li\u003e\n\u003cli\u003eChecking an expired test kit’s accuracy\u003c\/li\u003e\n\u003cli\u003eCalibrating your refractometer\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Fauna Marin","offers":[{"title":"Default Title","offer_id":40508811837575,"sku":"FM056","price":13.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/products\/fauna-marin-multi-reference-100ml-663653.jpg?v=1731256412"},{"product_id":"aqua-one-hydrometer-with-thermometer","title":"Aqua One Hydrometer with Thermometer","description":"\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003e\u003cspan\u003eThis Aqua One Marine Glass Thermometer \/ Hydrometer floats and is easy to read. Green bar indicates the prefered temperature \/ salt level for most aquariums.\u003c\/span\u003e\u003cbr\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eFloating Glass Hydrometer with Thermometer\u003c\/li\u003e\n\u003cli\u003eFor Saltwater Aquariums\u003c\/li\u003e\n\u003cli\u003eEasy Accurate Reading\u003c\/li\u003e\n\u003cli\u003e10 - 50C\u003c\/li\u003e\n\u003cli\u003eIndicators for safe range\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!----\u003e","brand":"Aqua One","offers":[{"title":"Default Title","offer_id":41830339772551,"sku":"10308","price":3.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/files\/AquaOneHydrometer.jpg?v=1731258055"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0563\/6387\/6487\/collections\/RefractomerRedSeaX360X360X.webp?v=1734435610","url":"https:\/\/charterhouse-aquatics.com\/collections\/refractometers-hydrometers\/saltwater.oembed","provider":"Charterhouse Aquatics","version":"1.0","type":"link"}