PPM to dKH Converter
Convert alkalinity reported as ppm CaCO3, dKH, meq/L, or mmol/L, then compare the result with reef and freshwater target ranges.
🧪Quick Presets
⚖Alkalinity Inputs
📊Conversion Reference
| Alkalinity Unit | Conversion From dKH | Conversion To dKH | Common Test Reading |
|---|---|---|---|
| ppm as CaCO3 | dKH x 17.848 | ppm / 17.848 | KH kits, pool-style kits |
| meq/L | dKH x 0.357 | meq/L x 2.8 | Reef chemistry references |
| mmol/L as CaCO3 | dKH x 0.1783 | mmol/L x 5.608 | Lab style alkalinity |
| German degrees KH | Primary display | Primary display | Aquarium KH and reef alk |
🎯Reef and Freshwater Target Ranges
| Aquarium Type | Target dKH | ppm as CaCO3 | meq/L |
|---|---|---|---|
| Low nutrient reef | 7.0 to 8.0 | 125 to 143 | 2.50 to 2.86 |
| Mixed reef | 7.5 to 9.5 | 134 to 170 | 2.68 to 3.39 |
| SPS reef | 7.5 to 8.5 | 134 to 152 | 2.68 to 3.04 |
| Fish-only marine | 8.0 to 12.0 | 143 to 214 | 2.86 to 4.29 |
| Freshwater community | 3.0 to 8.0 | 54 to 143 | 1.07 to 2.86 |
| Planted freshwater | 2.0 to 5.0 | 36 to 89 | 0.71 to 1.79 |
| African cichlid | 10.0 to 18.0 | 178 to 321 | 3.57 to 6.43 |
| Neocaridina shrimp | 3.0 to 8.0 | 54 to 143 | 1.07 to 2.86 |
| Caridina shrimp | 0.0 to 2.0 | 0 to 36 | 0.00 to 0.71 |
| Outdoor pond | 5.0 to 12.0 | 89 to 214 | 1.79 to 4.29 |
🧴Adjustment Product Reference
| Adjustment Type | Calculator Basis | Best Use | Planning Note |
|---|---|---|---|
| Sodium bicarbonate dry | 3.00 g per 100 L per 1 dKH | Gentle alkalinity lift | Small pH effect |
| Sodium carbonate dry | 1.89 g per 100 L per 1 dKH | Stronger alkalinity lift | Higher pH effect |
| Balanced dry mix | 2.35 g per 100 L per 1 dKH | General planning | Verify label strength |
| Two-part alk liquid | 1.0 meq per mL default | Reef daily dosing | Use tested consumption |
| Saturated kalkwasser | 0.04 meq per mL estimate | Slow replacement water | Limited by evaporation |
| Calcium reactor effluent | Effluent strength estimate | Continuous reef supply | Tune by daily testing |
| Water change only | Blend current and new dKH | Lowering or correcting | Depends on percent changed |
📏Common Aquarium Volumes
| Tank Size | Approx Dimensions | Metric Volume | 1 dKH Bicarbonate |
|---|---|---|---|
| 10 gallon | 20 x 10 x 12 in | 38 L | 1.1 g |
| 20 long | 30 x 12 x 12 in | 76 L | 2.3 g |
| 40 breeder | 36 x 18 x 16 in | 151 L | 4.5 g |
| 55 gallon | 48 x 13 x 21 in | 208 L | 6.2 g |
| 75 gallon | 48 x 18 x 21 in | 284 L | 8.5 g |
| 125 gallon | 72 x 18 x 21 in | 473 L | 14.2 g |
Alkalinity are a measurement of the buffering capacity in water. Alkalinity is also a measurement that determines how stable the pH level of the water remain. Alkalinity levels directly affect the ability of corals and other invertebrate to produce there skeletons.
Additionally, alkalinity levels also directly impact the stress levels of fish in the tank. There are different test kit that can measure alkalinity in the tank. For instance, you can measure alkalinity in ppm as calcium carbonate, German degree of carbonate hardness, or in units of milliequivalents per liter.
How to Use the Alkalinity Converter for Your Tank
Each of these unit has a different value from the other units of measurement for alkalinity, so a converter is necessary to translate one unit of measurement to another unit of measurement for alkalinity. Furthermore, the alkalinity converter will allow you to compare alkalinity levels to you’re target alkalinity range. Therefore, it will allow you to compare alkalinity levels without having to perform the calculations yourself with the converter.
The alkalinity converter will require you to make several input into the converter to calculate your alkalinity proper. For example, you will have to input the volume of your tank. The size of your tank will determine the amount of alkalinity supplement that you have to add to your water.
A 75-gallon tank will require more alkalinity supplement than a 13-gallon tank because there is more water in the 75 gallon tank. Additionally, you must also select a target range for alkalinity for your tank. For instance, if you have a reef tank, the target alkalinity will be different than a freshwater tank with shrimp in it.
The alkalinity converter will use the target alkalinity range to calculate how much alkalinity you need to add to your tank to reach your target. There are different scenarios that the alkalinity converter will calculate for you depending on your goal for your alkalinity levels. For instance, you can either want to raise your alkalinity levels to a new target, maintain your alkalinity levels despite the consumption of alkalinity by the tank inhabitant, or you can want to adjust your alkalinity by changing the water in the tank.
Additionally, you will also have to select the product that you will use to increase the alkalinity levels to ensure that the alkalinity supplement spread evenly throughout the tank. For instance, you can use sodium bicarbonate or sodium carbonate. The alkalinity converter will account for the difference in strength of alkalinity product to make sure that you dont have to remember the different coefficient for each supplement.
One common error with alkalinity is using the Total Dissolved Solids (TDS) reading of the water to calculate the amount of alkalinity supplement to add to the tank. TDS measures the total number of dissolved element in the tank, while alkalinity in ppm as calcium carbonate measures the buffering capacity of the tank. Therefore, you should not use TDS readings to calculate alkalinity dose for the tank.
Using TDS readings will result in supplement doses being provided to the tank that are not the same as alkalinity reading, and can lead to incorrect alkalinity levels in the tank. Additionally, the inhabitant of the tank also consumes alkalinity levels in the tank. Corals and macroalgae will consume alkalinity every day.
As a result, alkalinity levels in the tank will drop over time due to the consumption by these inhabitant. There is also a safety limit built into the alkalinity converter for daily change to alkalinity levels to prevent any potential damage to the animals in the tank. High alkalinity level can be damaging to the corals and fish in the aquarium.
Therefore, you can use the alkalinity converter to set a limit to how much alkalinity level can change daily in the tank. The alkalinity supplement can then be spread over several day to reach the desired alkalinity level while adhering to the safety limit. Additionally, if you decide to use a water change to change the alkalinity levels in the tank, you can use the blend calculation to determine the alkalinity level of the tank after the water change is performed.
The reference table included with the alkalinity converter can show the mathematical calculation behind the unit conversions of alkalinity. For instance, the tables will show that one degree of hardness is equal to 17.85 ppm of calcium carbonate. These tables are provided in case you would like to manually enter each coefficient in the tank for a specific alkalinity product.
However, you should of used the alkalinity converter. While the alkalinity converter will provide you with an estimate of the amount of alkalinity supplement that you have to add to your tank, you have to still test the alkalinity of your tank multiple times. Due to the evaporation of water from the tank and the biological activity in the tank, alkalinity level will change.
As a result, you have to test alkalinity levels in the tank frequent to make sure that levels remain in your target range. Testing alkalinity levels and adjusting alkalinity supplement according to the tests are the best means of maintaining alkalinity in your aquarium water.
