2 Part vs. Kalkwasser Slurry vs. Calcium Reactor - The Right Calcium & Alkalinity Tool Guaranteed
Kalkwasser
Kalkwasser or calcium hydroxide solution is honestly the best choice for a majority of hobbyists. It will sufficiently supply enough calcium and alkalinity for most low to medium-demand reef aquariums which include Soft Corals, LPS, and even mixed reef tanks containing SPS corals.
Pros
- Balanced calcium to alkalinity ratio
- The single solution maintains both major elements
- Does not increase salinity with sodium or chloride
- It's very affordable
- Provides a significant boost to pH
Cons
- Kalkwasser is a dilute solution so you will need to dose considerably more fluid each day compared to something like a two-part solution which does require a larger storage bin. Estimate a container that can hold 10% of your tank's total water volume.
- If your tank does not evaporate enough freshwater to accommodate the amount of kalkwasser solution you need, you won't be able to add enough without diluting your salinity level.
- If your tank has a naturally elevated pH that stays at 8.3 or more without any help, kalkwasser will cause dangerous spikes in pH.
- Not designed to make large adjustments to your specific calcium/alkalinity levels. It is designed for regular maintenance only.
- Does not contain trace elements.
- Best added with a metered dosing pump and should not be dosed manually
Two-Part Solution
The ever-popular 2 part solution is a system of two different concentrated additives that are designed for equal additions into the aquarium. It will sufficiently supply enough calcium and alkalinity for all reef aquariums, from low-demand mixed reef tanks to high-demand SPS corals, 2-part will work. The best choice for new reef tank owners.
Pros
- It does contain trace elements and magnesium
- Can be dosed manually
- It's concentrated, easy to mix, and doesn't require large storage space
- A versatile solution for any reef tank, no matter the demand or size
- Chemicals are generally safe to use and forgiving if you mess up
- Affordable when you use bulk chemicals
- Has a positive impact on pH
- Easy to dial-in and dose properly use Reef Tank Calculators
Cons
- Can increase salinity over time with excess sodium and chloride if your not regularly changing your water.
- Requires daily addition of two separate additives.
- More expensive than Kalkwasser; especially with SPS aquariums with heavy demand.
- Less impact on pH compared to Kalkwasser.
Calcium Formate
Tropic Marin's All-For-Reef is the most popular additive that contains Calcium Formate and it is a unique solution. It is a single, concentrated additive that can be dosed with or without trace elements. It will be able to keep up with almost any reef aquarium but does become quite expensive with larger tanks. Great for new reef tank owners or those with nano tanks.
Pros
- The single solution supplies both calcium and alkalinity - easy to use
- No impact on pH meaning it is great for beginners and small aquariums
- Available with or without trace elements
- No salinity increases with excess sodium & chloride like you get with a two-part solution
- Very concentrated, does not require considerable storage space
Cons
- Can be very expensive, especially in high-demand aquariums
- Does not elevate pH
- Can be difficult to dial in the correct dose
- Requires precision dosing and is not as forgiving as two-part solution
- Does not have immediate measurable results; it takes time to increase alkalinity levels.
Calcium Reactor
The most complex and expensive solution but also the most automated. This is the best solution for high-demand aquariums and will supply a very consistent level of calcium and alkalinity in very well-established reef aquaria.
Pros
- Saves money in the long run but has a considerable up-front investment
- Requires very little maintenance
- Easy to use when controlled with a pH controller
- Maintains very stable levels of both calcium and alkalinity
- Eliminate the need for dosing altogether
Cons
- Not great for low-demand or NEW aquariums
- Considerable initial investment
- Will suppress pH
- Requires advanced equipment
- Can elevate phosphate levels
- Does not supply sufficient trace elements.
With over 25 years of experience keeping aquariums of all kinds, Robert has a detailed understanding of advanced aquarium techniques and theory. Working as a professional content creator in the saltwater aquarium industry for over 18 years, his perspective, thoughtfulness for the hobbyist, and a general understanding of the hobby, and industry that surrounds it, allows Robert to write and create digestible content that makes reefing fun and easy.
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