Reef Dosing Calculator

Calculate exact dosing amounts for calcium, alkalinity, and magnesium supplements. Select your product, enter your tank parameters, and get precise dosing instructions with safety recommendations.

NSW Calcium
420 ppm
NSW Alkalinity
7–8 dKH
NSW Magnesium
1280 ppm

🧪 Calcium Dosing

Dosing Results

To raise calcium by 40 ppm using BRS 2-Part Calcium

2000
Total mL
405.76
Total tsp
1000
mL / dose
202.88
tsp / dose

📋 Recommended Schedule

Split into 2 doses of 1000 mL (202.88 tsp) each:

  • • Dose 1: 1000 mL — wait 1 hour before next dose
  • • Dose 2: 1000 mL — wait 1 hour before next dose

Retest parameters 1 hour after the final dose.

💡 Dosing Tips

  • ✓Test before dosing. Always verify your current parameters with a reliable test kit before adding any supplements.
  • ✓Dose to a high-flow area like your sump return section. Never dose directly onto corals or livestock.
  • ✓Calcium and alkalinity are linked. When you raise one, the other may drop. Always dose both and keep them in balance.
  • ✓Avoid large swings. Raising calcium by more than 50 ppm or alkalinity by more than 2 dKH at once can stress corals. Split into multiple doses.
  • ✓Magnesium matters. Low magnesium makes it difficult to maintain calcium and alkalinity. Check magnesium first if your levels won't stabilize.
  • ✓Use actual water volume, not tank display size. Subtract rock, sand, and equipment displacement — typically 15–20% less than rated volume.

Track Your Parameters Over Time

One-time dosing gets you there, but consistent tracking keeps you there. With My Reef Log you can log every water test, visualize calcium, alkalinity, and magnesium trends, and dial in your dosing schedule perfectly.

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