Carbon Conundrum; Trying to fill the gaps in my aquatic husbandry knowledge.

[Scott Stevenson]

I use mechanical and biological filtration and have a solid understanding of the nitrogen cycle, but I am trying to understand how things work if I were to set up a tank with carbon filtration. I have no plans to start using carbon filtration and am just trying to add to my knowledge base.

Is it even possible for a tank to be cycled using a carbon filter and can live plants do well in a carbon filter situation? Would ferts even be effective or would the carbon just neutralize them?

[lefty o]

you can 100% have a cycled tank with carbon. carbon is good for removing things from an aquarium that you dont want. it doesnt absorb bacteria. it can absorb meds, nutrients, chemicals etc. the key thing with carbon is that it does well at absorbing things, but only does so for a short time before it has absorbed all it can. after that it is pretty much an inert substance. it is a handy tool, and it has its time and place for use, beyond being a money maker for filter manufacturers. 

[Widgets]

Carbon is used for chemical filtration. It removes some organic and inorganic toxins. It does not do anything for Ammonia, Nitrites, or Nitrates. It will fairly quickly absorb what it can, then it can only provide surface area for the beneficial bacteria to grow on.

The best use for carbon, if you choose to use it, is as a quick cleanup after treatment with medication, or for tannin removal (it the colored water bothers you).

Here is a link to more information on carbon. 

https://www.thesprucepets.com/activated-carbon-in-the-aquarium-1380929

Edited April 10, 2022 by Widgets

[Scott Stevenson]

Ok cool, I knew carbon did not absorb the bacteria, but I thought that maybe it absorbed the ammonia to a point that BB would not have a chance to colonize the tank.

 

[nabokovfan87]

On 4/10/2022 at 1:25 PM, Scott Stevenson said:

Is it even possible for a tank to be cycled using a carbon filter and can live plants do well in a carbon filter situation? Would ferts even be effective or would the carbon just neutralize them?

The carbon will absorb "things" and it could be nitrates, it could be nitrites, could be ammonia, could be phosphate or iron or meds.

For a planted tank the general advice is to run carbon when you first setup the tank (before plants) or when you are finishing dosing meds.  This is one of the best ways to "clean" a tank in terms of making sure there isn't any abnormalities in the water itself.  It would be the freshwater analogy of using RODI water in some capacity. Obviously RODI filters involve more than carbon blocks and do a much better job at removing things.

So let's say you had a pretty bad water source, on a well, and you were having issues with cloudy water or poor water to start with. I'd actually run carbon on that tank and then go ahead and setup a dosing pump to dose daily. Perfom bi-weekly water changes and then week 1 you run carbon, week 2 you run without.  You could also set it up to "condition" the water with carbon elsewhere and then use that pre-filtered water for your water change and dose normally without a risk of removing something the plants need.

Edited April 10, 2022 by nabokovfan87

[Scott Stevenson]

On 4/10/2022 at 4:50 PM, nabokovfan87 said:

So let's say you had a pretty bad water source, on a well, and you were having issues with cloudy water or poor water to start with. I'd actually run carbon on that tank and then go ahead and setup a dosing pump to dose daily. Perfom bi-weekly water changes and then week 1 you run carbon, week 2 you run without.  You could also set it up to "condition" the water with carbon elsewhere and then use that pre-filtered water for your water change and dose normally without a risk of removing something the plants need.

Interesting. does carbon than do a good job of removing chlorine and chloramine? I run water straight from the tap into my tanks and then use water conditioner and that seems to work fine, but I know my town "messes" with the water in the spring/summer and I have been considering setting up some type of water holding/conditioning tank for the summer.

[nabokovfan87]

On 4/10/2022 at 3:09 PM, Scott Stevenson said:

Interesting. does carbon than do a good job of removing chlorine and chloramine? I run water straight from the tap into my tanks and then use water conditioner and that seems to work fine, but I know my town "messes" with the water in the spring/summer and I have been considering setting up some type of water holding/conditioning tank for the summer.

Yep, That is specifically the purpose of carbon blocks in RODI systems.  You are doing everything correctly. The carbon we'd use in a HoB is a lot more of a "filtering over time" concept, while something like RODI filtration is going to strip everything completely from the water due to how that mechanism operates.

You can't rely on HoB carbon to remove all of the chlorine/chloramine within a few seconds because there's no guarantee all of those molecules are going to make their way into the HoB or that they will be absorbed first pass.

Edited April 10, 2022 by nabokovfan87