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Calcimator

Reef Dosing Calculator

Calcium, alkalinity, and magnesium dosing for reef tanks.

Inputs

Results

Calcium Chloride Dose (grams)

58

Soda Ash Dose (grams)

15.3

Calcium Chloride (tsp)10.5
Soda Ash (tsp)2.7
Baking Soda Alternative (grams)34.2
Daily Ca Maintenance (grams)14.5
Daily Alk Maintenance (grams)10.2
Estimated Mg Supplement (grams)29
Calcium Dose Grams57.97
Alk Teaspoons Baking Soda6.01
How to Use This Calculator
  1. Enter Tank Volume (gallons), Current Calcium (ppm), and Target Calcium (ppm).
  2. Set Current Alkalinity (dKH) and Target Alkalinity (dKH).
  3. Review Calcium Chloride Dose (grams) and Soda Ash Dose (grams).
  4. Use Calcium Chloride (tsp) and Soda Ash (tsp) to inform your decision.

How the result changes with Target Calcium (ppm)

Target Calcium (ppm)Calcium Chloride Dose (grams)Soda Ash Dose (grams)
320015.3
370015.3
43072.515.3
480144.915.3

What each input means

Tank Volume (gallons)
Total system water volume including sump.
Current Calcium (ppm)
Your current calcium test result in ppm. Reef target: 400-450 ppm.
Target Calcium (ppm)
Desired calcium level. 420 ppm is a good target for mixed reef.
Current Alkalinity (dKH)
Your current alkalinity test result in dKH. Reef target: 7-9 dKH.
Target Alkalinity (dKH)
Desired alkalinity level. 8-9 dKH is ideal for most reef tanks.

What each result means

Calcium Chloride Dose (grams)
Grams of CaCl2·2H2O (Dowflake) to reach target calcium.
Calcium Chloride (tsp)
Teaspoons of CaCl2·2H2O for easier measuring.
Soda Ash Dose (grams)
Grams of soda ash (Na2CO3) to reach target alkalinity.
Soda Ash (tsp)
Teaspoons of soda ash for easier measuring.
Baking Soda Alternative (grams)
Grams of baking soda (NaHCO3) as an alternative alk supplement.
Daily Ca Maintenance (grams)
Estimated daily calcium chloride dose to offset moderate coral consumption (~10 ppm/day).
Daily Alk Maintenance (grams)
Estimated daily soda ash dose to offset moderate coral consumption (~1 dKH/day).
Estimated Mg Supplement (grams)
Rough magnesium sulfate dose to maintain Ca:Mg balance.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Tank Volume (gallons) = 50, Current Calcium (ppm) = 380, Target Calcium (ppm) = 420, Current Alkalinity (dKH) = 7 = 5 input(s) provided
  2. Calculate Calcium Chloride Dose
    Calcium Chloride Dose = (calciumDeficit * tankVolume) / 34.5
    58 = 58
  3. Calculate Soda Ash Dose
    Soda Ash Dose = (alkDeficit * tankVolume) / 4.91
    15.3 = 15.3
  4. Calculate Calcium Chloride
    Calcium Chloride = calciumGrams / 5.5
    10.5 = 10.5
  5. Calculate Soda Ash
    Soda Ash = alkGramsSodaAsh / 5.7
    2.7 = 2.7

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