Introduction

This article explains how to maintain or raise calcium, alkalinity and magnesium using cheap and available additives.

The article is based on Reef App - Dosing calculator

How is the amount of additive calculated.

Before you use the calculator

Be sure to carefully measure the parameter you want to adjust before you add any additives to your aquarium.
You can do so by using one of the many high quality testkits for marine aquaria.

If you don't know what to measure, the following would be a good start:

  • Calcium - Ca - Recommended level: 420 ppm
  • Alkalinity - Recommended level: 8 dKH / 2.85 mEq/l
  • Magnesium - Mg - Recommended level: 1350 ppm

I need to higher parameter levels

You can use the calculator to help you determine how much additive is needed to reach the target value.
Choose the parameter you want to raise, choose which additive to use and enter the actual value and the target value for this parameter.

Magnesium should be adjusted first, when you reach the desired magnesium level you can start adjusting the others.

I need to lower parameter levels

First you have to identify the cause for the high parameter levels.

Common causes for high parameter levels:

  1. High salinity due to bad measuring equipment etc. If you add too much salt you also higher calcium, alkalinity and magnesium.
  2. Use of tap water. You might slowly raise the calcium level due to the calcium in the drinking water.
  3. Salt with a high level of calcium, alkalinity or magnesium
  4. Wrong usage of additives
When you have found and eliminated the cause, then slowly lower the parameter levels by changing water.
If you have stony corals, these might also consume some of the minerals which helps lowering the parameter levels.

Maintaining parameter levels

Before you start calculating how much to need to maintain parameter levels, you need to make sure all your parameters are close to the optimal level.

Calcium - Ca

  1. Measure Ca using a high quality testkit.
  2. Wait 3-4 days then measure alkalinity again.
  3. Calculate the difference between the two measurements and divide it by the number of days you have waited.
  4. Open the calculator and choose "Calcium - Ca".
  5. Choose which additive to use. Additives which specify X g/l are liquids.
  6. Enter the latest measurement into the "Actual value"-field and the difference from the previous step into the "Daily consumption"-field.
  7. The result shows how much to add pr. day, the first few days you might have to add a little extra as shown.
  8. Remeber to measure Ca, alkalinity and Mg regularly in the beginning when you start using an additive

Alkalinity

  1. Measure alkalinity using a high quality testkit.
  2. Wait 1-2 days then measure alkalinity again.
  3. Calculate the difference between the two measurements and divide it by the number of days you have waited.
  4. Open the calculator and choose either "Alkalinity (dKH)" or "Alkalinity (mEq/l)" based on which unit your testkit uses.
  5. Choose which additive to use. Additives which specify X g/l are liquids.
  6. Enter the latest measurement into the "Actual value"-field and the difference from the previous step into the "Daily consumption"-field.
  7. The result shows how much to add pr. day, the first few days you might have to add a little extra as shown.
  8. Remeber to measure Ca, alkalinity and Mg regularly in the beginning when you start using an additive

Magnesium - Mg

  1. Measure Mg using a high quality testkit.
  2. Wait 7-14 days then measure Mg again.
  3. Calculate the difference between the two measurements and divide it by the number of days you have waited.
  4. Open the calculator and choose "Magnesium - Mg".
  5. Choose which additive to use. Additives which specify x g/l are liquids mixes.
  6. Enter the latest measurement into the "Actual value"-field and the difference from the previous step into the "Daily consumption"-field.
  7. The result shows how much to add pr. day, the first few days you might have to add a little extra as shown.
  8. Remeber to measure Ca, alkalinity and Mg regularly in the beginning when you start using an additive

IMPORTANT NOTE:
Do not perform water change or add any additive to your aquarium while you are following the steps above.

Calcium - Ca

Most aquaria with stony corals needs a calcium additive to maintain a optimal level of calcium.

The most common additive for calcium is calcium chloride (dihydrat).
It can be used in its solid form or you can dissolve it in water for use with a dosing pump.

Recipes for liquid dosage

Hans-Werner balling: 71.6 g / liter RO water (Recommended for aquaria with low Ca consumption)
Higher consentration balling: 400 g / liter RO water (Recommended for aquaria with high Ca consumption)

Alkalinity

Most aquaria with stony corals needs an additive to maintain alkalinity at a optimal level.

The most common additive for alkalinity is sodium bicarbonate.
It can be used in its solid form or you can dissolve it in water for use with a dosing pump.
Sodium carbonate can also be use, but it is more consentrated and it has a greater influence on pH.

IMPORTANT NOTE:
Some manufactors sells "Carbonate mix". These might be a mix of sodium bicarbonate and sodium carbonate, so can't use the predefined additives in the calculator.

There are two common units for measuring alkalinity, dKH and mEq/l.
The calculator has a predefined parameter for both, please make sure you choose the one matching your testkit.

Recipe for liquid dosage

Hans-Werner balling: 84 g / liter RO water

Magnesium

Some aquaria might have a need for regular dosage of magnesium additives, but many will be fine with regular water change.

The most common additive for magnesium is magnesium chloride (hexahydrat).
It can be used in its solid form or you can dissolve it in water for use with a dosing pump.
Some manufactors mix magnesium chloride (hexahydrat) and magnesium sulfate (heptahydrate).

Recipe for liquid dosage

Common consentration: 400 g / liter RO water

References

Balling

Aqua Fair - Hans-Werner balling (German)

Parameters and units in general

Reefkeeping - Reef Aquarium Water Parameter
Reefkeeping - The Units of Measure of Reefkeeping

Additives

Wikipedia - Calcium chloride
Wikipedia - Sodium bicarbonate
Wikipedia - Sodium carbonate
Wikipedia - Magnesium chloride
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