{"product_id":"red-sea-calcium-pro-reagent-refill-kit","title":"Red Sea Calcium Pro Reagent Refill Kit","description":"\u003cp\u003e\u003cstrong\u003eThree reagents, seventy-five more tests, same titrator.\u003c\/strong\u003e This is the genuine Red Sea reagent refill for the Calcium Pro Test Kit — Red Sea part R21406, restocking Reagents A, B and C so the kit reads calcium to a resolution of 5 ppm again. The titrator, dosing spoon, syringe and glassware you already own stay exactly where they are.\u003c\/p\u003e\n\u003cp\u003eCalcium is not the parameter that runs out fastest, but it is the one people stop testing when the reagent runs low — and a reef dosing Foundation A blind is a reef heading somewhere you did not choose.\u003c\/p\u003e\n\n\u003ch3\u003eKey features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eGenuine Red Sea part R21406\u003c\/strong\u003e — the same three-reagent set supplied in the complete kit R21405.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAll three reagents in one box\u003c\/strong\u003e — Reagent A, the powdered Reagent B and the Reagent C titrant, so nothing is left half-stocked.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e5 ppm resolution\u003c\/strong\u003e — tight enough to see a 20 ppm daily change, which is the maximum Red Sea considers safe.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTitration to a colour change\u003c\/strong\u003e — the endpoint is a clear shift rather than a judgement call against a printed card.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCheaper and less wasteful than a second kit\u003c\/strong\u003e — the titrator is the expensive part and it does not wear out.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat's included\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eReagent A\u003c\/li\u003e\n\u003cli\u003eReagent B (powder)\u003c\/li\u003e\n\u003cli\u003eReagent C (titrant)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eTogether these restore the kit to its full 75-test count.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eNot included:\u003c\/strong\u003e the professional titrator, the 5 mL syringe, the dosing spoon for the powdered reagent, the glass vial, the colour reference card, the instruction manual and the storage case. This is chemistry only.\u003c\/p\u003e\n\u003cp\u003eIf this would be your first Red Sea calcium test, buy the \u003ca href=\"\/products\/red-sea-calcium-pro-testing-kit-75-tests\"\u003eRed Sea Calcium Pro Testing Kit\u003c\/a\u003e instead — without the titrator and the dosing spoon there is no way to run the test.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eManufacturer part number\u003c\/th\u003e\n\u003ctd\u003eR21406\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eRefill for\u003c\/th\u003e\n\u003ctd\u003eRed Sea Calcium Pro Test Kit (R21405)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter measured\u003c\/th\u003e\n\u003ctd\u003eCalcium\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTest method\u003c\/th\u003e\n\u003ctd\u003eTitration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTests restored\u003c\/th\u003e\n\u003ctd\u003e75\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eResolution\u003c\/th\u003e\n\u003ctd\u003e5 ppm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMeasuring range\u003c\/th\u003e\n\u003ctd\u003eUnlimited — a titration reads to its endpoint rather than off a fixed scale\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eReagents supplied\u003c\/th\u003e\n\u003ctd\u003eReagent A, Reagent B (powder), Reagent C (titrant)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWater type\u003c\/th\u003e\n\u003ctd\u003eMarine and reef\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eStorage\u003c\/th\u003e\n\u003ctd\u003eClosed, 15–25 °C, out of direct sunlight\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eWhat calcium should I be running?\u003c\/h3\u003e\n\u003cp\u003eRed Sea publishes calcium targets as a trade-off between how fast corals grow and how well they colour up. Higher calcium and alkalinity push growth; lower figures favour coloration.\u003c\/p\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eSystem\u003c\/th\u003e\n\u003cth\u003eCalcium target\u003c\/th\u003e\n\u003cth\u003eWhat Red Sea says you get\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMixed reef\u003c\/th\u003e\n\u003ctd\u003e465 ppm\u003c\/td\u003e\n\u003ctd\u003eExceptional growth, good coloration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMixed reef\u003c\/th\u003e\n\u003ctd\u003e450 ppm\u003c\/td\u003e\n\u003ctd\u003eGreat growth, great coloration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMixed reef\u003c\/th\u003e\n\u003ctd\u003e430 ppm\u003c\/td\u003e\n\u003ctd\u003eGood growth, exceptional coloration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSPS dominant\u003c\/th\u003e\n\u003ctd\u003e465 ppm\u003c\/td\u003e\n\u003ctd\u003eExceptional growth, good coloration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSPS dominant\u003c\/th\u003e\n\u003ctd\u003e430 ppm\u003c\/td\u003e\n\u003ctd\u003eGreat growth, great coloration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSPS dominant\u003c\/th\u003e\n\u003ctd\u003e410 ppm\u003c\/td\u003e\n\u003ctd\u003eGood growth, exceptional coloration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFrag system\u003c\/th\u003e\n\u003ctd\u003e465 ppm\u003c\/td\u003e\n\u003ctd\u003eExceptional growth, good coloration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eUltra-low nutrient system\u003c\/th\u003e\n\u003ctd\u003e410 ppm\u003c\/td\u003e\n\u003ctd\u003eGood growth, exceptional coloration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eWhat to do when the reading is off\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eBelow your target:\u003c\/strong\u003e dose \u003ca href=\"\/products\/red-sea-reef-care-calcium-foundation-a\"\u003eRed Sea Foundation A (Calcium+)\u003c\/a\u003e, or the \u003ca href=\"\/products\/red-sea-reef-care-calcium-foundation-a-powder\"\u003epowdered Foundation A\u003c\/a\u003e if you mix your own stock solution. Red Sea states a maximum safe rise of 20 ppm in one day.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAbove your target:\u003c\/strong\u003e stop dosing and let coral demand pull it back. Calcium sitting high alongside high alkalinity risks precipitation, which strips both at once and coats heaters and pump impellers in white scale.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eReading correct but corals still not growing:\u003c\/strong\u003e calcium is rarely the limiting factor on its own. Test alkalinity and magnesium before you add any more calcium — low magnesium in particular makes both of the others impossible to hold.\u003c\/p\u003e\n\n\u003ch3\u003eHow often to test\u003c\/h3\u003e\n\u003cp\u003eRed Sea's guidance is to test three days after starting a new dosing regime to see how fast the tank is consuming calcium, then settle into weekly testing once the dose is dialled in.\u003c\/p\u003e\n\u003cp\u003eAlways check salinity first and allow ten minutes after any adjustment before drawing a sample. A tank that has just had top-up water added will read low for reasons that have nothing to do with calcium.\u003c\/p\u003e\n\n\u003ch3\u003eCare and handling\u003c\/h3\u003e\n\u003cp\u003eLevel the powdered Reagent B in the dosing spoon rather than heaping it — an over-full spoon is the most common cause of a Calcium Pro result that reads high and will not reconcile with anything else.\u003c\/p\u003e\n\u003cp\u003eStore all three reagents closed, between 15 and 25 °C, in the kit's case and away from prolonged light. Red Sea states the reagents are stable up to the date printed on the pack when stored that way. Keep them away from acids, oxidising compounds and bare metal.\u003c\/p\u003e\n\n\u003ch3\u003eSafety\u003c\/h3\u003e\n\u003cp\u003eReagent A is the one to respect. Red Sea's safety data sheet lists sodium hydroxide at 10–25% with the signal word \u003cstrong\u003eDanger\u003c\/strong\u003e: it may be corrosive to metals and it causes severe skin burns and eye damage. Wear eye protection and gloves, and do not decant it into an unlabelled container.\u003c\/p\u003e\n\u003cp\u003eReagent C contains EDTA at 1–5% and a trace of sodium hydroxide, carries the signal word \u003cstrong\u003eWarning\u003c\/strong\u003e, and is an eye irritant. Reagent B is not classified as hazardous.\u003c\/p\u003e\n\u003cp\u003eKeep all three out of reach of children. For eye contact, rinse with water for at least 15 minutes and seek medical attention. For skin contact, remove affected clothing and wash thoroughly with soap and water. If swallowed, do not induce vomiting — rinse the mouth and get medical advice.\u003c\/p\u003e\n\n\u003ch3\u003eSuitable for, and not suitable for\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eSuitable for:\u003c\/strong\u003e owners of the Red Sea Calcium Pro Test Kit who have run down any of the three reagents, and reef keepers dosing a calcium supplement who need better resolution than a colour-comparison kit provides.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eNot suitable for:\u003c\/strong\u003e freshwater calcium or general hardness testing. It will not serve Red Sea's older Marine Care calcium kit, which uses different chemistry, and it is not a standalone product — there is no titrator in the box.\u003c\/p\u003e\n\n\u003ch3\u003eGoes well with\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/red-sea-calcium-pro-testing-kit-75-tests\"\u003eRed Sea Calcium Pro Testing Kit\u003c\/a\u003e — the complete kit this refill restocks.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/red-sea-reef-care-calcium-foundation-a\"\u003eRed Sea Foundation A (Calcium+)\u003c\/a\u003e — the supplement you meter against the result.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/red-sea-alkalinity-pro-reagent-refill-kit\"\u003eRed Sea Alkalinity Pro Reagent Refill\u003c\/a\u003e — the partner parameter; calcium and alkalinity are consumed together.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/red-sea-magnesium-pro-reagent-refill-kit\"\u003eRed Sea Magnesium Pro Reagent Refill\u003c\/a\u003e — the parameter that holds the other two up.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/red-sea-reef-care-skeletal-elements-foundation-abc-1kg\"\u003eRed Sea Skeletal Elements Foundation ABC+ 1 kg\u003c\/a\u003e — all three foundation elements in one powder.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/red-sea-reef-foundation-pro-multi-testing-kit\"\u003eRed Sea Reef Foundation Pro Multi Test Kit\u003c\/a\u003e — calcium, alkalinity and magnesium in a single case.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWarranty and delivery\u003c\/h3\u003e\n\u003cp\u003eAny manufacturer warranty Red Sea offers applies in addition to your rights under the Australian Consumer Law, which are not limited or excluded by it.\u003c\/p\u003e\n\u003cp\u003eShips as a standard small parcel. Reagent volumes are well under the threshold for dangerous goods freight.\u003c\/p\u003e\n\n\u003ch3\u003eCommon questions\u003c\/h3\u003e\n\u003ch4\u003eHow many tests does the Red Sea Calcium Pro reagent refill provide?\u003c\/h4\u003e\n\u003cp\u003eThe refill restores the Calcium Pro Test Kit to its full 75-test count, which is the figure Red Sea specifies for the complete kit.\u003c\/p\u003e\n\u003ch4\u003eWhat comes in the Calcium Pro refill?\u003c\/h4\u003e\n\u003cp\u003eThree reagents: Reagent A, the powdered Reagent B, and Reagent C, which is the titrant. The titrator, dosing spoon, syringe, glass vial, colour card and case are not included — they come with the complete kit and are meant to last across many refills.\u003c\/p\u003e\n\u003ch4\u003eWhat is the Red Sea part number for the Calcium Pro refill?\u003c\/h4\u003e\n\u003cp\u003eThe refill is Red Sea part R21406 and the complete kit is R21405. Red Sea's safety data sheet covers both under one document because the chemistry is identical.\u003c\/p\u003e\n\u003ch4\u003eMy calcium reads correctly but my corals are not growing. Is the test wrong?\u003c\/h4\u003e\n\u003cp\u003eUsually not. Calcium, alkalinity and magnesium are consumed together, and a correct calcium figure alongside low alkalinity or low magnesium will still stall growth. Test all three before adding more calcium.\u003c\/p\u003e\n\u003ch4\u003eIs Reagent A dangerous?\u003c\/h4\u003e\n\u003cp\u003eIt requires care. Red Sea classifies Reagent A with the signal word Danger — it contains 10–25% sodium hydroxide, causes severe skin burns and eye damage, and may corrode metals. Wear gloves and eye protection, keep it in its original labelled bottle, and store it out of reach of children.\u003c\/p\u003e\n\u003ch4\u003eWhy does my result change if I heap the powder?\u003c\/h4\u003e\n\u003cp\u003eReagent B is measured by volume with the supplied spoon, so a heaped spoon puts more reagent into the vial than the method assumes and shifts the endpoint. Level the spoon against the edge of the container every time and results become repeatable.\u003c\/p\u003e","brand":"RedSea","offers":[{"title":"Default Title","offer_id":54774152102179,"sku":"RED250a","price":45.95,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0972\/7236\/5347\/files\/Red_Sea_Calcium_Pro_-_Refill.jpg?v=1782112632","url":"https:\/\/nicksaquariumoceanariumterrarium.com.au\/products\/red-sea-calcium-pro-reagent-refill-kit","provider":"Nicks Aquarium Oceanarium Terrarium","version":"1.0","type":"link"}