CalMag Calculator

Select Your Water Source

Your water source is crucial as it determines the base mineral content of your solution. Different water sources contain varying levels of calcium, magnesium, and other minerals.

Water Source

Select your primary water source. This will help determine if additional mineral content needs to be considered. Different water sources have different properties:

RO Water: Virtually mineral-free, perfect base for precise nutrient control
Rain Water: Generally low in minerals, may vary by region and collection method
Tap Water: Mineral content varies by location, check local water reports
Well Water: Can have high mineral content, testing recommended

Water Mineral Content

Please provide the mineral content of your water if known. You can usually find this information from your water supplier or through a water test.

Calcium

Magnesium

Don't know your water's mineral content?

Check your water supplier's website for a water quality report
Search online using your postal code + "water quality report" or "water analysis"
Use a water testing kit from your local garden center or hydroponics store
Contact your water supplier directly for detailed information
Consider professional water testing services for accurate results
Check your latest water bill - it may include mineral content information
Join local gardening groups - members often share water analysis data
Use online water quality databases specific to your region

Search Online

Click below to search for your water quality report:

Search Water Analysis

Choose Your Fertilizer

The fertilizer choice is crucial as it determines the base ratio of calcium to magnesium in your solution. Select a pre-configured fertilizer or choose "No fertilizer used" to create a custom mix.

Fertilizer

Select a fertilizer to be added to your water. It is assumed that the fertilizer is a solution with the concentration given in parentheses. Consider these factors when choosing your fertilizer:

Pre-mixed fertilizers often have specific Ca:Mg ratios
The ratio affects nutrient availability and plant uptake
Choose based on your plant's growth stage and needs
Consider selecting "No fertilizer" for custom additive mixing

Select Additives

Additives help fine-tune your nutrient solution. Choose calcium and magnesium additives and their concentrations to achieve the perfect balance for your plants.

Calcium additive

Concentration in %

Enter the concentration of the additive here. The concentration is used to calculate the amount of additive to be added.

Magnesium additive

Concentration in %

Enter the concentration of the additive here. The concentration is used to calculate the amount of additive to be added.

Tips for additive selection and concentration:

Higher concentrations mean less volume needed but require more precise measuring
Lower concentrations are more forgiving but require larger volumes
Consider solubility limits when setting concentrations
Some additives may affect pH - check product documentation

Final Settings

Configure the final parameters for your calculation, including the target ratio, solution volume, and calculation model.

Calcium / Magnesium ratio

The ratio of calcium to magnesium should ideally be 3.5. However, this ratio can also be adjusted as desired.

Water volume in L

Enter the volume of your water here. The volume is used to calculate the amount of fertilizer and additive to be added.

Dilution with distilled water

If your water has too high values, it may be useful to dilute the water.

Model

Select the model you want to use. Whether linear or dynamic (Ca, Mg, Ca/Mg) is up to you and your preferences.

Understanding the settings:

Ca:Mg Ratio: 3.5:1 is common, but may vary by plant type and growth stage
Volume: Calculate total solution needed for your system
Model Selection:
- Linear/Fumu: Consistent ratios throughout growth
- PPP-Ca: Optimized for calcium-heavy feeding
- PPP-Mg: Optimized for magnesium-heavy feeding
- PPP-Ca/Mg: Dynamic ratio adjustment
Dilution Support: Enable if your water has high mineral content