{"product_id":"brs-kalkwasser-calcium-hydroxide","title":"BRS Kalkwasser | Calcium Hydroxide Reef Supplement (Ca + KH + pH)","description":"\u003cstyle\u003e\n  .aq-pd { font-family: Georgia, serif; color: #1a1a1a; max-width: 860px; margin: 0 auto; line-height: 1.7; }\n  .aq-pd h2 { font-size: 1.45em; font-weight: 700; letter-spacing: -0.01em; border-left: 4px solid #FF5722; padding-left: 12px; margin: 2em 0 0.6em; }\n  .aq-pd p { margin: 0.5em 0 1em; }\n  .aq-callout { background: #1a1a1a; color: #fff; border-radius: 4px; padding: 16px 20px; margin: 1.6em 0; font-family: Arial, sans-serif; font-size: 0.93em; line-height: 1.6; }\n  .aq-callout strong { color: #f5c518; }\n  .aq-features { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 14px; margin: 1em 0 1.6em; }\n  .aq-feature-card { background: #f4f4f4; border-radius: 4px; padding: 14px 16px; border-left: 3px solid #FF5722; font-family: Arial, sans-serif; font-size: 0.9em; }\n  .aq-feature-card strong { display: block; margin-bottom: 3px; color: #1a1a1a; }\n  .aq-feature-card span { color: #555; }\n  .aq-specs-table { width: 100%; border-collapse: collapse; margin-top: 1em; font-family: Arial, sans-serif; font-size: 0.93em; }\n  .aq-specs-table th { background: #1a1a1a; color: #fff; text-align: left; padding: 9px 14px; font-weight: 600; letter-spacing: 0.04em; text-transform: uppercase; font-size: 0.82em; }\n  .aq-specs-table td { padding: 8px 14px; border-bottom: 1px solid #e5e5e5; vertical-align: top; }\n  .aq-specs-table tr:nth-child(even) td { background: #f9f9f9; }\n  .aq-specs-table td:first-child { font-weight: 600; width: 45%; color: #444; }\n  .aq-compare-table { width: 100%; border-collapse: collapse; margin: 1em 0 1.6em; font-family: Arial, sans-serif; font-size: 0.93em; }\n  .aq-compare-table th { background: #1a1a1a; color: #fff; text-align: left; padding: 10px 14px; font-weight: 600; letter-spacing: 0.04em; text-transform: uppercase; font-size: 0.82em; }\n  .aq-compare-table td { padding: 9px 14px; border-bottom: 1px solid #e5e5e5; vertical-align: top; }\n  .aq-compare-table tr:nth-child(even) td { background: #f9f9f9; }\n  .aq-compare-table td:first-child { font-weight: 600; color: #444; }\n\u003c\/style\u003e\n\n\u003cdiv class=\"aq-pd\"\u003e\n\n  \u003cp\u003e\u003cstrong\u003eBRS Pharma-Grade Kalkwasser\u003c\/strong\u003e is a calcium hydroxide (Ca(OH)\u003csub\u003e2\u003c\/sub\u003e) supplement that maintains \u003cstrong\u003ecalcium\u003c\/strong\u003e, \u003cstrong\u003ealkalinity\u003c\/strong\u003e, and \u003cstrong\u003epH\u003c\/strong\u003e in saltwater reef aquariums in a single dose. Mix with RO\/DI water to make \"limewater,\" then drip it into your sump to replace evaporated water — the limewater simultaneously tops off your tank, raises pH, and replenishes the calcium and carbonate stony corals consume to build skeleton. Browse all \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/additives-supplements\"\u003ereef supplements \u0026amp; additives\u003c\/a\u003e or shop \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/salt-water\"\u003esaltwater supplies\u003c\/a\u003e.\u003c\/p\u003e\n\n  \u003cdiv class=\"aq-callout\"\u003e\n    \u003cstrong\u003eThe classic three-in-one reef supplement.\u003c\/strong\u003e One dose of saturated limewater raises \u003cstrong\u003ecalcium\u003c\/strong\u003e, \u003cstrong\u003ealkalinity\u003c\/strong\u003e, and \u003cstrong\u003epH\u003c\/strong\u003e together. Pharma-grade purity — no phosphate, silicate, or other reef-tank contaminants. Drip it into your sump as ATO replacement and skip the two-part dosing pumps.\n  \u003c\/div\u003e\n\n  \u003ch2\u003eWhat Kalkwasser Does\u003c\/h2\u003e\n  \u003cp\u003eIn a stocked reef tank, hard corals (SPS, LPS, clams) constantly pull calcium and carbonate out of the water to build skeleton. If you don't replace what they consume, calcium and alkalinity drop — the corals stop growing and eventually start receding. Kalkwasser is the simplest fix: \u003cem\u003ecalcium hydroxide\u003c\/em\u003e dissolved in your top-off water. Each gallon of limewater delivers roughly equal molar amounts of Ca\u003csup\u003e2+\u003c\/sup\u003e and OH\u003csup\u003e-\u003c\/sup\u003e, which means it raises calcium and alkalinity at the same ratio corals consume them. Bonus: the high-pH limewater also precipitates inorganic phosphate, keeping nuisance-algae fuel low.\u003c\/p\u003e\n\n  \u003ch2\u003eFeatures\u003c\/h2\u003e\n  \u003cdiv class=\"aq-features\"\u003e\n    \u003cdiv class=\"aq-feature-card\"\u003e\n\u003cstrong\u003e3-in-1 Reef Supplement\u003c\/strong\u003e\u003cspan\u003eRaises Ca, KH, and pH simultaneously in stoichiometric balance.\u003c\/span\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"aq-feature-card\"\u003e\n\u003cstrong\u003ePharmaceutical Grade\u003c\/strong\u003e\u003cspan\u003eUltra-pure calcium hydroxide — no phosphate or silicate contaminants.\u003c\/span\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"aq-feature-card\"\u003e\n\u003cstrong\u003eDrips Into ATO\u003c\/strong\u003e\u003cspan\u003eReplaces evaporation while dosing — no separate pumps needed.\u003c\/span\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"aq-feature-card\"\u003e\n\u003cstrong\u003ePhosphate Precipitation\u003c\/strong\u003e\u003cspan\u003eHigh-pH limewater binds inorganic PO\u003csub\u003e4\u003c\/sub\u003e, starving nuisance algae.\u003c\/span\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"aq-feature-card\"\u003e\n\u003cstrong\u003eEconomical\u003c\/strong\u003e\u003cspan\u003e2 tsp\/gal saturated solution — a 2 lb jar dosed daily lasts months.\u003c\/span\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"aq-feature-card\"\u003e\n\u003cstrong\u003eReefer-Approved\u003c\/strong\u003e\u003cspan\u003eThe original go-to for SPS-dominant tanks. Used since the 90s.\u003c\/span\u003e\n\u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eChoose Your Size\u003c\/h2\u003e\n  \u003ctable class=\"aq-compare-table\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpec\u003c\/th\u003e\n\u003cth\u003e2 lbs\u003c\/th\u003e\n\u003cth\u003e4 lbs\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eNet Weight\u003c\/td\u003e\n\u003ctd\u003e2 lbs (907 g)\u003c\/td\u003e\n\u003ctd\u003e4 lbs (1.81 kg)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eApprox. Limewater Yield\u003c\/td\u003e\n\u003ctd\u003e~700 gal saturated\u003c\/td\u003e\n\u003ctd\u003e~1,400 gal saturated\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBest For\u003c\/td\u003e\n\u003ctd\u003e20 – 90 gal reef tanks\u003c\/td\u003e\n\u003ctd\u003e90+ gal reefs \/ heavy SPS demand\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSKU\u003c\/td\u003e\n\u003ctd\u003e210812\u003c\/td\u003e\n\u003ctd\u003e210813\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch2\u003eHow to Mix \u0026amp; Dose\u003c\/h2\u003e\n  \u003cp\u003e\u003cstrong\u003e1. Mix saturated limewater.\u003c\/strong\u003e Add \u003cstrong\u003e2 teaspoons of kalkwasser per gallon of RO\/DI water\u003c\/strong\u003e in a sealed container (an ATO reservoir works perfectly). Shake or stir; the powder will not fully dissolve — that's normal. The clear liquid \u003cem\u003eabove\u003c\/em\u003e the settled powder is your saturated limewater (~2 g\/L CaO equivalent).\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003e2. Let it settle.\u003c\/strong\u003e Wait 1 – 2 hours for the undissolved powder to fall to the bottom. Only the clear liquid above gets dosed — never agitate the bottom sediment into your dosing line.\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003e3. Drip into the sump.\u003c\/strong\u003e Use the limewater as your top-off water. A standard ATO with a slow drip into a high-flow area of the sump is ideal. Dose \u003cem\u003eonly\u003c\/em\u003e at night for tanks with low CO\u003csub\u003e2\u003c\/sub\u003e at lights-on, or 24\/7 for stable systems.\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003e4. Refill when clear.\u003c\/strong\u003e When the liquid turns completely clear (no more white powder at the bottom), the calcium hydroxide has been consumed. Add more kalkwasser and repeat.\u003c\/p\u003e\n\n  \u003ch2\u003eSpecifications\u003c\/h2\u003e\n  \u003ctable class=\"aq-specs-table\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eBulk Reef Supply (BRS)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eProduct\u003c\/td\u003e\n\u003ctd\u003ePharma-Grade Kalkwasser\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eActive Ingredient\u003c\/td\u003e\n\u003ctd\u003eCalcium hydroxide — Ca(OH)\u003csub\u003e2\u003c\/sub\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eForm\u003c\/td\u003e\n\u003ctd\u003eDry powder\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eAvailable Sizes\u003c\/td\u003e\n\u003ctd\u003e2 lbs, 4 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eUse\u003c\/td\u003e\n\u003ctd\u003eSaltwater \/ reef calcium \u0026amp; alkalinity supplement\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eDosing\u003c\/td\u003e\n\u003ctd\u003e2 tsp per gal RO\/DI water; drip via ATO\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eSaltwater only — NOT for freshwater\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch2\u003eRecommended Pairings\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAn RO\/DI system or RO\/DI water — kalkwasser MUST be mixed with purified water, never tap\u003c\/li\u003e\n    \u003cli\u003eAn \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/water-testing\"\u003ealkalinity \u0026amp; calcium test kit\u003c\/a\u003e — dose to a target, not a guess\u003c\/li\u003e\n    \u003cli\u003eBrowse all \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/additives-supplements\"\u003ereef supplements \u0026amp; additives\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eBrowse \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/salt-water\"\u003esaltwater supplies\u003c\/a\u003e\n\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch2\u003eFAQ\u003c\/h2\u003e\n  \u003cp\u003e\u003cstrong\u003eKalkwasser vs. two-part dosing — which should I use?\u003c\/strong\u003e\u003cbr\u003eKalkwasser is great for low-to-moderate demand reefs (mixed reef, soft corals, beginner SPS), and it has the unique benefit of precipitating phosphate. Two-part (calcium + alkalinity solutions dosed separately) scales to any consumption rate without the pH ceiling kalkwasser hits. Many advanced reefers use BOTH: kalkwasser as the main ATO method, two-part to top up the difference. For tanks demanding more than a few dKH\/day, two-part is needed.\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eWill it raise my pH too high?\u003c\/strong\u003e\u003cbr\u003eLimewater is high-pH (~12 in concentrated form, but heavily diluted as it enters the tank). In a well-aerated, low-CO\u003csub\u003e2\u003c\/sub\u003e reef, kalkwasser typically raises tank pH from ~7.9 to a healthy 8.2 – 8.4. If pH spikes above 8.4, slow the drip rate or dose only at night when respiratory CO\u003csub\u003e2\u003c\/sub\u003e is highest.\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eCan I dose it directly into the tank?\u003c\/strong\u003e\u003cbr\u003eNo. Limewater must drip slowly into a high-flow area (typically the sump). Direct dosing into the display will cause localized pH spikes that can burn corals and stress fish.\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eHow long does a 2 lb jar last?\u003c\/strong\u003e\u003cbr\u003eFor a typical 40 – 75 gallon reef tank evaporating ~1 gal\/day, a 2 lb jar of kalkwasser lasts \u003cstrong\u003e4 – 6 months\u003c\/strong\u003e. The 4 lb jar lasts roughly twice as long. The exact duration depends on calcium demand from your coral load.\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eIs it safe for freshwater tanks?\u003c\/strong\u003e\u003cbr\u003eNo. Kalkwasser is for saltwater reef use only. The pH and calcium levels it produces are not appropriate for freshwater systems.\u003c\/p\u003e\n\n\u003c\/div\u003e\n","brand":"Bulk Reef Supply","offers":[{"title":"2 lbs","offer_id":48498856067291,"sku":"210812","price":19.99,"currency_code":"USD","in_stock":true},{"title":"4 lbs","offer_id":48498856100059,"sku":"210813","price":33.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0767\/5209\/3403\/files\/210812-brs-exb-kalkwasser-2lbs-additive-fr_1.webp?v=1774103809","url":"https:\/\/squeakysaquatics.com\/products\/brs-kalkwasser-calcium-hydroxide","provider":"Squeaky's Aquatics","version":"1.0","type":"link"}