When you hear about people putting vodka or sugar in their aquarium, you may think they are crazy. But the reality is doing so can be beneficial to your aquarium. Adding these substances to your tank is called carbon dosing. It is not the same thing as adding activated carbon to your aquarium, despite the fact that they are both ‘carbon.’ This type of carbon dosing is a method to manage your aquariums nutrients –– primarily nitrate and phosphate, which can slow coral growth; cause corals to turn brown; and/or lead to nuisance algae growth.
What is Carbon Dosing and How Does it Work?
Carbon (the element C, not active active carbon or charcoal) is a building block for all living things. It is frequently is in short supply in a reef aquarium. Carbon dosing is the act of adding available carbon to your ecosystem. The most common forms of carbon dosing are vodka (Yes, the stuff you can drink.), sugar, vinegar, biopellets and carbon supplements.
Providing carbon helps all organisms. However, the bacteria in the aquarium are the primary beneficiaries. Carbon is a food source for these bacteria. As the bacteria reproduce they consume excess nutrients in the tank, mainly phosphate and nitrate. This reduction of nutrients / pollution in the aquarium greatly increases water quality, reduces algae growth and improves coral color and growth. Read more details on how this works here.
Pros and Cons of Carbon Dosing
Carbon dosing is generally very safe. However, there are a few things that should be considered. The primary risk is overdosing. However, careful planning and starting off slowly will generally yield safe results. If overdosing occurs, it is not the carbon source that is the problem. It is the proliferation of bacteria. The bacteria in your aquarium are very efficient at taking advantage of the available carbon. They can reproduce so quickly that it consumes all of the oxygen available in the water column and your fish and coral can actually suffocate. Yikes!
So, how do you prevent bacteria from sucking up all the oxygen in your aquarium? Thankfully, the solution is simple – use a good protein skimmer.
Using a skimmer will remove any excessive bacteria and ensure good oxygenation of the water. Please note that you may see a change in the actual color or quantity of the skimmate being produced.
Pros of Carbon Dosing:
- Inexpensive
- Easy
- No Additional Equipment Needed
Cons of Carbon Dosing:
- Must Be Started Slowly
- Can Be Dangerous If Overdosed
- Can Strip Tank of Needed Nitrate & Phosphate
Forms of Carbon Dosing and Pros and Cons of Each
The following are the most commonly used sources of organic carbon:
Vodka Dosing
Pros:
- Readily available
- Pure
- Inexpensive
Cons:
- Best suited for use with a dosing pump
- Some may not want alcohol in the home
Vinegar Dosing
Pros:
- Readily available
- Pure – Food grade
- Inexpensive
Cons:
- Causes slight reduction in pH
- Best suited for use with a dosing pump
Sugar Dosing
Pros:
- Readily available
- Pure – Food grade
- Inexpensive
- Very Concentrated – A little goes a long way
Cons:
- Difficult to dose a consistent amount
- Easy to overdose
Biopellets
Pros:
- Easy to use. Just set it and forget it
- Less chance of overdose
Cons:
- Requires bio-pellet reactor
- Higher upfront costs
- Not quite as effective as other methods
Carbon Supplements (Like ATI Nutrition)
Pros:
- Easy to Calculate Recommended Dose
- Product Support Available
Cons
- Expensive
- Best suited for use with a dosing pump
- Actual mechanism of product is unknown
There you have it. Dosing carbon is very effective, safe and can be used on any saltwater aquarium – fish only, FOWLR (fish only with live rock), or full reef. It is generally very safe as long as it is not overdosed and is always used with a protein skimmer. Carbon dosing will help coral growth and coloration by lowering excess nutrient levels. Due to the low cost and overall effectiveness for most tanks, it’s something most aquarists should consider.