What is the Bolus Method for Reef Tanks

Bolus Method Background - pH

I'm going to level with you, this part of the article may be more information that you really want. It is going to talk a bit more about the chemistry. If you do not understand, or do not care to know, feel free to skip this part. It's really just the nerdy "why" behind the science.

Frag Farm and Fauna Marin indicate that there are 2 major components behind pH. The first being the buffer system (what we usually simplify to "alkalinity"), and photosynthesis. Both of these play an important role in pH value and stability. Be warned, the buffer system can be a bit complicated though as it really talks about the equilibrium of alkalinity to pH and CO2.

Buffer System

Specifically, we are going to talk about the carbonate buffer system used by coral. This system uses carbonates to buffer against the change in pH by absorbing acids. It also provides carbonate and bicarbonate ions for the coral to build their skeleton.

When talking about the direction of equilibrium, when equilibrium shifts "left" it means the pH is lower, and "right" is a higher pH. When CO₂ is dissolved in water, it creates Carbonic Acid (H₂CO₃). This is considered a weak acid, meaning it will give up a Hydrogen ion easily. When interacting with water, the carbonic acid can then convert into Bicarbonate (HCO₃). So essentially, bicarbonate ions and carbonic acid can become a little bit of a back and forth, making the true concentration of carbonates difficult to determine because it is a calculation of both pH and alkalinity.

So the buffer system consists of Carbonic Acid (H₂CO₃), Bicarbonate (HCO₃^-), and Carbonate (CO₃^2-). The difference between the three of these is just the number of hydrogen atoms. pH being a measure of hydrogen in the water, indicates that more hydrogen, the lower the pH.

The premise is that when alkalinity is dosed, your aquarium has to spend time to rebalance itself across these three ions. The demonstration of this is when bicarbonate is added, the pH has a sudden drop. This shows the conversion to carbonic acid. The pH then raises as the aquarium rebalances itself.

Another reference made is the "Carbonic Acid Battery". This is refering to how carbonic acid in the water can degass the CO₂ in the protein skimmer, sacrificing come bicarbonate to improve pH.

The 2nd factor, photosynthesis, also has a strong affect on pH. The photosynthesis process consumes CO₂, Bicarbonate, Water, and light. The coral will then produce sugars. With a higher rate of photosynthesis, more CO₂ will e consumed by the coral. This will then increase the reef tank's pH.

This is where the Bolus method argues that pH should not be controlled by chemicals such as kalkwasser, but rather by the coral photosynthesis to create the same high pH.

Benefits of the Bolus Method

The Bolus method will provide benefits to the reef tank such as pH elevation, tank stability, and reduced precipitation that leads to old-tank-syndrome. This method also focussed on improved coral growth and improved photosynthesis.

How to do the Bolus Method

Before You Start

Before starting the Bolus method, they indicate that your Calcium should be between 400 and 435 ppm (mg/l), Magnesium should be between 1300 and 1450 ppm (mg/l) and Alkalinity should be between 7 and 9 dKh. They also encourage an ICP test to ensure everything is relatively in range, and calibrating any pH probes you may use. You will then need to calculate ho`w much alkalinity your tank consumes.

How to Determine Alkalinity Consumption in a Reef Tank

Lighting

The total lighting period should be no more than 11 hours. There are a few different phases, or periods, that this is broken down into. The SOLUS period, remaining photoperiod, and lights out.

The first lighting period is right as the lights turn on. This is called the SOLUS period. For the beginning of your photoperiod, you should turn all lights on right away, with no ramp up period. The intention behind this sudden light burst is to "supercharge" photosynthesis.

The first part of the lighting period is when coral tend to be the most effective at absorbing light and producing sugars for the coral. So rather than wasting a portion of this time for slow ramping, the Bolus method encourages using this time to give the most light possible.

You will also increase the white lights you typically provide by about 20% and keep the blue lights at the same value you would normally set them at. After 20 minutes, this 20% can be set back to what you would normally keep it at. Over a couple weeks, this 20 minutes should be expanded to 2 or 3 hours. Observe your coral to determine what duration is best.

For the remaining photoperiod, keep your lights at the normal level. Remembering that the total photoperiod, including the SOLUS period, should be no more than 11 hours.

Alkalinity, Calcium, and Magnesium Dosing

Alkalinity

The dosing method mentioned is the Fauna Marin Balling Light carbonate. This is a Bicarbonate mix 2-part dosing component (not soda ash). For this method, you will take the entire amount of alkalinity that you would dose for the entire day, and add it all at once. Specifically, you will add all of this 30 minutes before the lights come on. This is VERY important to the Bolus method! The dosing needs to be added to the last chamber (return) of the sump, or a very high flow area of the tank.

The intention behind this is to provide the maximum amount of carbonate to the coral during the initial part of the photosynthesis where it is most effective. This will also provide an improved pH for this initial period.

Make sure to monitor alkalinity, measuring at the same time every day, ideally when the pH is highest. The pH should be highest at the end of the photoperiod. This will give you a general idea of how much alkalinity is used daily, and then you can change your dose accordingly. Just don't add or remove more than 5% at a time, with 2% being called out as ideal.

Calcium

You will then start dosing calcium 1 hour after the bolus dose is done for alkalinity. The calcium should be spread out over the photoperiod, but not dosed after the lights are out. Calcium should be kept between 400 and 435ppm, as precipitation will rapidly increase at 440ppm.

Magnesium

Magnesium should be dosed over the full 24 hour period. Ideally keeping levels between 1300 and 1450 ppm. The slightly higher level is to help balance the chemistry with the bolus dose.

Resources

• Fauna Marin Bolus Method PDF

More About the Bolus Method

Conclusion

The Bolus Method of reef keeping has definitely peaked my interest. With the stabilization of alkalinity and pH with minimal work, and improved coral growth, its hard not to at least think about. What are your thoughts? Let me know!

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About the Author

John Krenzer

John is a Software Engineer with a passion for saltwater aquariums, as well as the founder and president of Reef Stable. He started in the aquarium hobby as a child with a 20 gallon freshwater aquarium. His interest in aquarium life grew and in 2008, John set up his first saltwater aquarium.

Today, John maintains an over 300 gallon reef tank system, consisting of a 120g reef and a 210g reef. These large tanks are contained within the same system, sharing a sump as a means to reduce total maintenance and increase total water volume.

John writes articles for the blog as a means to learn about more reef aquarium topics. These articles act as a reference for the readers as well as himself. John updates these articles frequently to provide additional information or make corrections as new information becomes available.

If you would like to request an article, tank tour article, or to collaborate, let me know via the Contact Me Page!

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