{
  "_meta": {
    "title": "Hot tub chemical dosing reference",
    "publisher": "HotTubCalc (hottubcalc.com)",
    "methodology": "Doses in ounces by weight at 200/350/500-gallon reference sizes, computed from published water-chemistry dosage rates and product available-halogen fractions; generated at build time by the same math as the dosing calculator and checked by build-time assertions. Doses scale linearly with volume.",
    "browseable": "https://hottubcalc.com/guides/hot-tub-dosing-chart/",
    "citeAs": "HotTubCalc (hottubcalc.com)",
    "license": "Free to cite with attribution."
  },
  "generatedAt": "2026-07-27",
  "unit": "oz (weight)",
  "sizes": [
    200,
    350,
    500
  ],
  "rows": [
    {
      "label": "Raise total alkalinity +10 ppm",
      "product": "alkalinity-up",
      "chem": "sodium bicarbonate",
      "values": {
        "200": 0.48,
        "350": 0.84,
        "500": 1.2
      }
    },
    {
      "label": "Raise free chlorine +3 ppm",
      "product": "sanitizer-chlorine",
      "chem": "dichlor granules",
      "values": {
        "200": 0.14,
        "350": 0.25,
        "500": 0.36
      }
    },
    {
      "label": "Raise bromine +3 ppm",
      "product": "sanitizer-bromine",
      "chem": "bromine granules",
      "values": {
        "200": 0.13,
        "350": 0.23,
        "500": 0.33
      }
    },
    {
      "label": "Lower pH 7.8 to 7.5",
      "product": "ph-down",
      "chem": "sodium bisulfate",
      "values": {
        "200": 1.5,
        "350": 2.62,
        "500": 3.75
      }
    },
    {
      "label": "Chlorine shock (+10 ppm)",
      "product": "shock-chlorine",
      "chem": "dichlor",
      "values": {
        "200": 0.48,
        "350": 0.83,
        "500": 1.19
      }
    },
    {
      "label": "Non-chlorine shock (routine)",
      "product": "shock-mps",
      "chem": "potassium monopersulfate",
      "values": {
        "200": 0.8,
        "350": 1.4,
        "500": 2
      }
    }
  ],
  "ranges": {
    "ph": {
      "min": 7.2,
      "max": 7.8,
      "ideal": 7.5,
      "unit": ""
    },
    "totalAlkalinity": {
      "min": 80,
      "max": 120,
      "ideal": 100,
      "unit": "ppm"
    },
    "freeChlorine": {
      "min": 3,
      "max": 5,
      "ideal": 4,
      "unit": "ppm"
    },
    "bromine": {
      "min": 4,
      "max": 6,
      "ideal": 5,
      "unit": "ppm"
    },
    "calciumHardness": {
      "min": 150,
      "max": 250,
      "ideal": 200,
      "unit": "ppm"
    },
    "cyanuricAcid": {
      "min": 20,
      "max": 50,
      "ideal": 30,
      "unit": "ppm"
    }
  },
  "constants": {
    "alkalinityUpOzPerGalPpm": 0.00023999999999999998,
    "dichlorAvailableChlorine": 0.56,
    "bromineAvailable": 0.6
  },
  "sources": [
    "Sodium bicarbonate raises total alkalinity about 10 ppm per 1.5 lb in 10,000 gallons (standard pool/spa dosage tables; Taylor Technologies; Trouble Free Pool PoolMath).",
    "Dichlor (sodium dichloro-s-triazinetrione dihydrate) is about 56 percent available chlorine; dosing is by available-halogen content (1 mg/L product per 1 mg/L residual, divided by the available fraction).",
    "Bromine granules / BCDMH are about 60 percent available bromine; spa bromine is carried at 4 to 6 ppm.",
    "Balanced-water ranges follow common spa water-care guidance (PHTA/APSP ranges and typical spa product labels): pH 7.2 to 7.8, total alkalinity 80 to 120 ppm, free chlorine 3 to 5 ppm, bromine 4 to 6 ppm.",
    "pH adjuster rates are representative spa-label increments and are buffer-dependent estimates; always add in small steps and retest."
  ]
}