The Salty Side: Saltwater Aquariums for Beginners

What Does Dosing a Saltwater Aquarium Mean?

dose a saltwater aquarium

A huge draw to reef keeping is the ability to keep, grow and sell live coral. In order to do so you will at some stage begin dosing a saltwater aquarium. By dosing you are establishing and maintaining an environment suitable for corals to flourish. In this article we look at what it means to dose a saltwater aquarium.

What is dosing a saltwater aquarium?

Generally speaking, in new systems, regular water changes will successfully provide your tank with the major and trace elements it needs. These elements are initially utilised by coralline algae and snails (for shell growth), then as you add hard corals (LPS and SPS), they too will begin to deplete the available elements because they use them for skeletal growth. 
Once you reach a point where water changes are no longer sufficient to provide for the needs of your inhabitants, dosing becomes a viable option to maintain the appropriate levels.

Manual dosing of saltwater elements

Dosing is simply the action of adding elements to your aquarium that otherwise would not have been available to your coral with water changes alone. The three main elements tested are alkalinity (KH), calcium (Ca) and magnesium (Mg).

Most new hobbyists will begin dosing by testing for these three parameters and realising they are becoming or have become depleted. If they had done their research, the depletion was to be expected. 

The next step is to work out what the take-up rate, or depletion rate, is per day and calculate how much to dose to replenish the loss.

Manual dosing means measuring out your elements and adding them daily by hand, but it has its drawbacks. It requires that you are always there to dose, and that you don’t forget to dose. As your reef tank grows it becomes more demanding, which means elements are utilised quicker. If you are adding elements once a day you are potentially creating unwanted fluctuations in levels.

This is a good way to start, but eventually the progression is normally towards automatic dosing.

What is auto dosing a saltwater aquarium?

Using an auto-dosing unit, such as the Kamoer F4 Pro Dosing Pump  or the cheaper Jebao Auto Dosing Pump the ensures that you can maintain constant levels at all times. This is done by programming the doser to add the requirement a number of times over a 24 hour period.

The initial outlay can be expensive, but the results are worth it.
Your responsibility becomes testing levels once a week, and ensuring the dosing containers are full for the doser to administer the KH buffer, or calcium, or magnesium.

Of course, as well as alkalinity, calcium and magnesium being the most important of elements to maintain in the reef tank, there are also trace elements to consider.

I auto dose KH, Ca and Mg using a Kamoer Doser. I also add trace elements and amino acids on a daily basis, but manually.

Kamoer F4 PRO 4 heads aquarium doser pump WiFi dosing pump with remote control for reef aquariums marine lives
  • F4 PRO is mainly used to quantitatively add aquarium additives, such as Ca, Mg and KH supplements. It easily maintains water quality and greatly reduces the user workload.
  • Basic parameters: 12V DC brush motor, pump tube size 2mm ID x 4mm OD, dimensions 270 x 87 x 49 mm, weight 950 g, flow rate >45 ml/min, titration times: 24 times/day - 1 time/99 days, titration accuracy: <±0.5%, volume range: 0.1 ml - 9999 ml. Reference noise value ≤54dB
  • F4 PRO uses plastic gear pump, no slipping and rusting. Use 4 kinds of color pump head, corresponding to 4 Easy to distinguish with 4 colors of connection tubes. Highly reliable threaded connectors are used to ensure no leakage problems. Standard with long-life imported pump tube.
Jebao Programmable Auto Dosing Pump DP-4, Black
  • Model :DP-4, Idea for Dosing CA / MG / AB Water or other liquid
  • 4 Channel Dosing Pump
  • Each Channel Provides 1 to 9999ml per day,24 timer per day

What is a dosing pump and how does it work?

A automatic dosing pump, once calibrated, injects the correct amount of KH buffer, calcium or magnesium into your tank on a daily basis. 

If, for instance, you would like to add 50ml of KH buffer per day to keep up with your coral uptake, you set the dosing pump to meter it out throughout a 24 hour period. Doing it this way ensures that the level of alkalinity doesn’t fluctuate by keeping levels balanced.

How do you set up a dosing pump for a saltwater aquarium?

The best setup is to mount the pump close to the dosing containers. Ideally speaking you would want the dosing lines to be as short as possible to prevent the build up of air bubbles that can potentially occur when the dosing unit is mounted far from the dosing containers.

This could be in your cabinet above the sump, or if you have a larger cabinet, in the electrical side.

Make sure the pump is accessible if you need to control it with a push button interface. There are WiFi dosing units however, that are only controlled by WiFi and its associated app as pictured above.

Dosing containers

Dosing containers come is all shapes and sizes. I like using the three compartment container because they neatly hold KH buffer, Calcium and Magnesium together.

Always make sure that your dosing line is higher than the water level to prevent backflow into you dosing containers.

Marinecolor® Acryli Made Liquid Storage Bucket 3 Rooms 4.5 Liters Storage Bucket, Working with Dosing Pump Reservoir ATO auto top Off System, with Scale Aquarium Air Pump Accessories
  • clear acryli made 3.8mm thick, 3 storage rooms, 4.5 liters,Capability : 1500mL/each room, Scale mark, size:31.8cm (12.5") X 10.8cm (4.25") X 17.5cm ( 6.89")
  • Versatile Aquatic Aid: Dive into effortless aquarium maintenance with our Acrylic Made Liquid Storage Bucket, engineered for seamless integration with dosing pumps, ensuring optimal water quality and aquatic health."
  • "Space-Saving Design: Maximize your aquarium space with our innovative 3-room liquid storage solution, offering a compact yet capacious 4.5-liter capacity to conveniently store various dosing supplements and additives."

What is 2 part dosing in a reef tank?

I have always dosed 3 part which includes KH buffer, calcium and magnesium. In addition to these 3 major elements I also manually does all the trace elements contained in two bottles. If I feel the tank needs it, I also dose amino acids separately. All of this takes a bit a time but I like the absolute control I have with it.

2 part dosing is basically the major elements, trace elements and amino acids combined in two bottles only. This means the dosing pump will be set to dispense just two solutions over a 24 hour period. 

Is dosing necessary in a saltwater tank?

If your intention is to keep SPS coral then the answer is a resounding yes. If you want to successfully keep LPS, although they are not as demanding as SPS they will definitely benefit from a stable system too.

Soft coral which includes corals such as mushrooms, Green Star polyp and Zoanthids are not that fussy. These can be maintained quite easily by doing regular water changes which will replenished used elements.

How often do you dose a reef tank?

This really does depend on what you are dosing. The rule of thumb would be to spread the desired amount into smaller doses over a 24 hour period to limit fluctuations.

Do soft corals need dosing?

Soft corals are far from delicate and are the easiest of all corals to keep. Dosing is not needed as long as they are accompanied by fish which will supply them with the nutrients they need (fish excrement). Carrying out regular water changes will also keep soft coral happy.

Just starting out in the hobby?
Get your copy of How To Set Up A Successful Saltwater Aquarium ebook today.

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How do you dose nitrates?

Some systems can become deficient in nutrients required by hard coral. If you find that you cannot raise you nitrates by feeding it might be time to look at dosing.

Read this article for more information.

How do you dose phosphates?

As with nitrates, phosphates can also fall below accepted levels.

Read this article for more information


A saltwater dosing pump can pretty much be used to dose anything into an aquarium, as long as it doesn’t need to be refrigerated or mixed prior to dosing.

It is undoubtedly one of the best tools you can add to a saltwater aquarium.

Hi, my name is Craig.
I am the owner of The Salty Side.
Firstly, thank you for visiting us. If you have found this article to be informative, and you now have a better understanding of the topic, then my job is done.

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