RedSea Refractometer

Red Sea's Seawater Refractometer offers exceptional accuracy, for measuring the absolute salinity of seawater at a temperature of 25oC

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.Main features of Red Sea's Seawater Refractometer include:Directly reads the absolute salinity of seawater at 25°C/77 0F ( No need for seawater or temperature compensation factors)Specifically designed for the ionic content of seawater (NSW) for more accurate salinity measurement (industry standard refractometers are calibrated for salt brine ).Calibrated for seawater (NSW) at 25oC/77oF, the normal temperature range for reef aquariums(most standard refractometers are calibrated at 15oC/59oF ).Easier to read, higher resolution display, focussed to the relevant range for reef aquariums of up to 40pptIncludes Integrated Automatic Temperature Compensation (ATC) for accurate measurement at standard ambient temperature.Red Sea's Refractometer displayThe 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 SalinitySalinity 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 & refractive indexAll 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 temperatureThe 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)

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Next Day Shipping Upgrade - Cut off is at 4:00 pm

Orders after that time will be processed the next working day

Please Note: We only deliver ponds and pond plants on our own delivery vehicles!

The blue highlighted area on the map below is where we deliver on our own vehicle! Unfortunately, if you are not in one of these postcode zones we are unable to deliver certain items such as plants, small glass items and selective other products.

We offer a few different delivery options depending on the size and value of your order.

Orders over £50 qualify for free mainland UK (excludes Northern Ireland) delivery which will arrive within 3-5 working days of the order being processed.

Residents of Northern Ireland, please provide your EORI or XI Number.

If you do not have one, please follow the information at https://www.gov.uk/eori

Orders Below £50 in Mainland UK will be charged a standard delivery fee of £5.99.

Additional Shipping Charges

For any orders that do not include Aquariums, the below is charged:

Next Working Day Parcel Delivery to Mainland UK - £7.99 OR £2.99 if the order is over £50

Standard Parcel Delivery to Northern Ireland £8.99

Standard Parcel Delivery to Scottish Highlands & Islands £9.99

Standard Parcel Delivery to Jersey & Guernsey £12.99

For all Aquarium deliveries (Excluding biOrbs & Smaller Aquariums), the below is charged:

Next Working Day Pallet Delivery - £20

2 Hour Booking Slot Pallet Delivery - £20

Pallet Delivery to Northern Ireland - £45

Pallet Delivery to Isle of Wight (PO36 and Above) and Scottish Highlands (AB, PH, IV1-36, IV, KW1-14, KY, PA21-41) - £45

Pallet Delivery to the Scottish Isles (KA27-28, PA60-90, ZE, JE, GY, IM, IV40-56, KW15-17, PH42-44, PA20, PA42-49) - £120

Pallet Delivery to Outer Hebrides (HS) - £140

• Red Sea Refractometer Manual