Terrible Advice Tuesdays (T.A.Tues): If you stop carbon dosing your tank, it will crash.
The rest of the story: Did you know that the end of the world is coming too?!
Let’s break this terrible advice down piece by piece.
First, when I think of a tank crashing, I think of a wide loss of fish and coral life within 72 hours.
Second, carbon dosing involves adding a carbon source to grow heterotrophic bacteria. These bacteria uptake phosphates and nitrates among other nutrients. (Note that heterotrophic bacteria are completely different from nitrifying bacteria. Also note that running activated carbon in your tank is NOT carbon dosing). The nutrient-rich bacteria is then exported from your tank usually via protein skimming. Over time, enough bacteria can be grown that your tank reaches a low nutrient or ultra-low (ULN) state where nitrates and phosphates are low enough that your test kit won’t detect them. Vodka dosing, biopellets and the Zeovit system are all examples of carbon dosing as discussed in my algae guide.
If you were to suddenly stop carbon dosing your tank, heterotrophic bacteria counts would drop and nutrient levels (nitrates and phosphates) would rise. How much will the nutrient levels rise? That will depend on lots of factors such as age of the tank, bioload levels, filtration on the tank, etc and an exact rise is impossible to calculate. Also, the bacteria counts will drop off slowly such that you could easily track the rise in nutrient levels and react to the situation.
A large rise in nitrate and phosphate levels would likely annoy and potentially kill your small-polyped stony (SPS) corals but it would take weeks not days. However, your large-polyp stony (LPS) corals and soft corals would probably celebrate that there was “junk” in the water and might look better after you stop carbon dosing!
What would your fish think about you stopping carbon dosing? They will care less.
And if your tank crashes immediately after you stop carbon dosing, something else was wrong.
If you are carbon dosing your tank and want to stop, do it slowly over the course of a month or more. As I’ve said lots of times before, saltwater tanks are like grumpy old men. They don’t want to change and if they do have to change, they want to do it slowly.Browse the Store! Questions?