{"product_id":"api-gh-and-kh-test-kit","title":"API GH\/KH Hardness Test Kit","description":"\u003cp\u003e\u003cstrong\u003eMeasures the two hardness numbers that decide how stable your pH will be.\u003c\/strong\u003e The API GH and KH Test Kit reads General Hardness (calcium and magnesium) and Carbonate Hardness (carbonate and bicarbonate, your tank's pH buffer) by drop-count titration — two reagent bottles, two glass test tubes, one instruction sheet.\u003c\/p\u003e\n\n\u003ch3\u003eKey features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTwo parameters, one kit\u003c\/strong\u003e — GH and KH each get their own dedicated reagent bottle and test tube.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTitration method, not a fixed test count\u003c\/strong\u003e — you count drops until the colour changes, so soft water uses fewer drops per test than hard water. See the note below.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eResults in degrees\u003c\/strong\u003e — read as °dGH and °dKH, with a conversion note in the instructions for converting to ppm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFreshwater and saltwater\u003c\/strong\u003e — the same reagents work for both.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow to use it\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eKH test:\u003c\/strong\u003e fill a test tube with a 5 mL water sample, add the KH solution one drop at a time, capping and inverting after each drop, and counting as you go. The test is complete when the sample changes from blue to yellow.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eGH test:\u003c\/strong\u003e fill a test tube with a 5 mL water sample, add the GH solution one drop at a time, capping and inverting after each drop, and counting as you go. The test is complete when the sample changes from orange to green.\u003c\/p\u003e\n\u003cp\u003eThe number of drops needed is the reading — each drop typically represents one degree of hardness, per the conversion chart printed in the instructions.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eAPI (Mars Fishcare)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMeasures\u003c\/th\u003e\n\u003ctd\u003eGeneral Hardness (GH) and Carbonate Hardness (KH)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMethod\u003c\/th\u003e\n\u003ctd\u003eLiquid reagent, drop-count titration\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eUnits\u003c\/th\u003e\n\u003ctd\u003eDegrees (°dGH \/ °dKH), convertible to ppm via the printed chart\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTests per kit\u003c\/th\u003e\n\u003ctd\u003eNot a fixed number — varies with water hardness, see below\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWater type\u003c\/th\u003e\n\u003ctd\u003eFreshwater and saltwater\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSKU\u003c\/th\u003e\n\u003ctd\u003eAA2295\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBarcode\u003c\/th\u003e\n\u003ctd\u003e317163010587\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFreight\u003c\/th\u003e\n\u003ctd\u003eStandard\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eWhy there's no fixed test count\u003c\/h3\u003e\n\u003cp\u003eUnlike API's colour-match kits, this is a titration test: you add reagent drop by drop until the colour flips, and the drop count itself is the reading. That means a soft-water tank (fewer drops needed) gets more tests out of the same bottle than a very hard-water tank (more drops needed per test). API does not publish a fixed test count for this reason, and quoting one would misrepresent how the kit works — so we haven't.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's included \/ what you'll still need\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIncluded:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eKH test reagent bottle\u003c\/li\u003e\n\u003cli\u003eGH test reagent bottle\u003c\/li\u003e\n\u003cli\u003eTwo glass test tubes with caps\u003c\/li\u003e\n\u003cli\u003eInstruction sheet with degree-to-ppm conversion\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eNot included:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eA printed colour chart — this kit reads by drop count and colour change, not a comparison card\u003c\/li\u003e\n\u003cli\u003eAnything to raise or lower hardness — test only\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSuitable for, and not suitable for\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eSuitable for:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eFreshwater and saltwater aquariums where GH and KH need tracking — planted tanks, shrimp tanks, African cichlids and reef systems all care about this pair\u003c\/li\u003e\n\u003cli\u003eDiagnosing pH instability — a low KH reading usually explains a pH that won't hold steady\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eNot suitable for:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCorrecting hardness — this kit measures only\u003c\/li\u003e\n\u003cli\u003eColour-blind users without assistance — the endpoint is a colour change, so a second person or a well-lit comparison helps\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSafety and handling\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eKeep out of reach of children.\u003c\/li\u003e\n\u003cli\u003eAvoid eye and skin contact with the reagents; rinse well with water if contact occurs.\u003c\/li\u003e\n\u003cli\u003eShake reagent bottles vigorously before use, and keep the cap closed tight while shaking.\u003c\/li\u003e\n\u003cli\u003eRinse test tubes immediately after each test to stop reagent residue staining the glass.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eGoes well with\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/api-freshwater-ph-test-kit\"\u003eAPI Freshwater pH Test Kit\u003c\/a\u003e — KH is what keeps a pH reading stable between tests, so the two go together.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/api-deluxe-ph-test-kit-with-liquid-adjusters\"\u003eAPI Deluxe pH Test Kit with Liquid Adjusters\u003c\/a\u003e — check KH before repeatedly dosing a pH adjuster into a tank that keeps drifting back.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/api-freshwater-master-multi-test-kit-5-in-1\"\u003eAPI Freshwater Master Multi Test Kit 5 in 1\u003c\/a\u003e — rounds out your routine testing with ammonia, nitrite and nitrate.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWarranty and delivery\u003c\/h3\u003e\n\u003cp\u003eThis is a consumable test kit, so no manufacturer warranty period applies. That does not affect your rights under the Australian Consumer Law: if the product is faulty, unsafe or not as described, you are entitled to a remedy. Ships as standard freight.\u003c\/p\u003e\n\n\u003ch3\u003eCommon questions\u003c\/h3\u003e\n\u003ch4\u003eWhy does this kit measure in drops instead of giving me a test count?\u003c\/h4\u003e\n\u003cp\u003eBecause it's a titration test — you add reagent until the colour changes, and the number of drops is the answer. Harder water needs more drops per test, so the exact number of tests you'll get from a bottle depends on your own water, not a fixed figure API can print.\u003c\/p\u003e\n\u003ch4\u003eWhat's the difference between GH and KH?\u003c\/h4\u003e\n\u003cp\u003eGeneral Hardness (GH) measures dissolved calcium and magnesium — the minerals many fish and plants need. Carbonate Hardness (KH) measures carbonate and bicarbonate, which buffer pH and stop it swinging with every water change or CO2 dose.\u003c\/p\u003e\n\u003ch4\u003eMy KH reads very low. Does that matter?\u003c\/h4\u003e\n\u003cp\u003eYes — low KH means little buffering capacity, so pH can swing quickly with small changes in the tank. If you're also seeing pH drift, low KH is often the underlying cause.\u003c\/p\u003e\n\u003ch4\u003eDoes this kit work for saltwater and reef tanks too?\u003c\/h4\u003e\n\u003cp\u003eAPI rates the reagents for both fresh and saltwater, though reef keepers chasing precise alkalinity for coral growth often prefer a dedicated marine alkalinity test alongside this one.\u003c\/p\u003e\n\u003ch4\u003eHow do I convert degrees to ppm?\u003c\/h4\u003e\n\u003cp\u003eThe instruction sheet included in the box carries a conversion table from °dGH\/°dKH to ppm. We haven't reprinted the exact conversion figures here, since we could not independently verify them from API's own published documentation.\u003c\/p\u003e","brand":"API","offers":[{"title":"Default Title","offer_id":55242285842723,"sku":"AA2295","price":36.95,"currency_code":"AUD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0972\/7236\/5347\/files\/api-gh-and-kh-test-kit-46120701100323.webp?v=1790239781","url":"https:\/\/nicksaquariumoceanariumterrarium.com.au\/products\/api-gh-and-kh-test-kit","provider":"Nicks AOT","version":"1.0","type":"link"}