GAC and running vs dosing carbon ?

[LadyTang2]

1. I understand carbon primarily removes organic compounds and some trace elements bound to those organic compounds. I've heard some say that GAC will lower nitrates and phos while others say it does not as GAC does not bind them directly. But wouldn't GAC ultimately reduce nitrate and phos since the organic compounds it removed would have later broken down into nitrate and phos?

2. Can GAC (assume I'm using rox .8) leak to some extent providing a carbon source for bacteria kinda like vinegar does, I'm guessing it's insignificant if at all?

3. Do I have the following terminology correct: "Running carbon" is like GAC in a reactor WHILE "dosing carbon" is like using vinegar for bacterial support?

 

[rmurken]

1. I understand carbon primarily removes organic compounds and some trace elements bound to those organic compounds. I've heard some say that GAC will lower nitrates and phos while others say it does not as GAC does not bind them directly. But wouldn't GAC ultimately reduce nitrate and phos since the organic compounds it removed would have later broken down into nitrate and phos?

2. Can GAC (assume I'm using rox .8) leak to some extent providing a carbon source for bacteria kinda like vinegar does, I'm guessing it's insignificant if at all?

3. Do I have the following terminology correct: "Running carbon" is like GAC in a reactor WHILE "dosing carbon" is like using vinegar for bacterial support?

1. GAC is not a particularly big player in nutrient control. It “polishes” the water by removing various organics and other compounds. For instance, gelbstoff, some odors, medications. But it’s not doing much to waste as it breaks down.

2. GAC is inorganic carbon and isn’t soluble. You need soluble organic carbon compounds to feed bacteria in the way “carbon dosing” does.

3. Correct.

 

[Randy Holmes-Farley Verified Community Expert]

1. I understand carbon primarily removes organic compounds and some trace elements bound to those organic compounds. I've heard some say that GAC will lower nitrates and phos while others say it does not as GAC does not bind them directly. But wouldn't GAC ultimately reduce nitrate and phos since the organic compounds it removed would have later broken down into nitrate and phos?

2. Can GAC (assume I'm using rox .8) leak to some extent providing a carbon source for bacteria kinda like vinegar does, I'm guessing it's insignificant if at all?

3. Do I have the following terminology correct: "Running carbon" is like GAC in a reactor WHILE "dosing carbon" is like using vinegar for bacterial support?

Yes on 1. It binds no nitrate and phosphate but will, to some extent, export N and P as organics.

No on 2. It is the wrong form of carbon. It is not just the solubility that matters. It cannot be digested by organisms. It is not an organic compound and few if any organisms can readily metabolize inorganic carbon to CO2 and thereby get energy.

Yes on 3.

 

[rmurken]

Yes on 1. It binds no nitrate and phosphate but will, to some extent, export N and P as organics.

No on 2. It is the wrong form of carbon. It is not just the solubility that matters. It cannot be digested by organisms. It is not an organic compound and few if any organisms can readily metabolize inorganic carbon to CO2 and thereby get energy.

Yes on 3.

Ah, thanks for clarifying and straightening my attempt at an answer out!

 

[p1u5h13r4m24]

Yes on 1. It binds no nitrate and phosphate but will, to some extent, export N and P as organics.

No on 2. It is the wrong form of carbon. It is not just the solubility that matters. It cannot be digested by organisms. It is not an organic compound and few if any organisms can readily metabolize inorganic carbon to CO2 and thereby get energy.

Yes on 3.

I know this is an old thread. Does GAC remove organic compounds that beneficial bacteria would need to consume to reproduce and grow. For example someone running a new tank (0 n&p) but aggressively using GAC may be starving their tank of organically to allow the bacteria population to grow?

Ah, thanks for clarifying and straightening my attempt at an answer out!

 

[Randy Holmes-Farley Verified Community Expert]

I know this is an old thread. Does GAC remove organic compounds that beneficial bacteria would need to consume to reproduce and grow. For example someone running a new tank (0 n&p) but aggressively using GAC may be starving their tank of organically to allow the bacteria population to grow?

GAC partly removes organic compounds that certain bacteria can consume.

What do you mean by beneficial bacterial?

I think people oversimplify what bacteria do, and I think it is unlikely that peopel suffer from "lack of beneficial bacteria" by using GAC.

If you are in a scenario where you are trying to increase bacteria (say, to try to fight an infestation of dinos) you may be better off adding organic matter as food for them than in reducing export of random organics that can have a variety of undesirable properties, from yellowing the water to being toxic.

 

[sixty_reefer]

I know this is an old thread. Does GAC remove organic compounds that beneficial bacteria would need to consume to reproduce and grow. For example someone running a new tank (0 n&p) but aggressively using GAC may be starving their tank of organically to allow the bacteria population to grow?

In addition to what Randy said, I would add that zero nitrates and phosphates will also be detrimental in allowing the beneficial bacteria in colonise the tank, more in particular the heterotrophic bacteria that will need nitrate, phosphates and a form of DOC to allow them to grow in your system. If you add organic carbon with zero nitrates and phosphates the results could be fairly detrimental to your system

 

[p1u5h13r4m24]

GAC partly removes organic compounds that certain bacteria can consume.

What do you mean by beneficial bacterial?

I think people oversimplify what bacteria do, and I think it is unlikely that peopel suffer from "lack of beneficial bacteria" by using GAC.

If you are in a scenario where you are trying to increase bacteria (say, to try to fight an infestation of dinos) you may be better off adding organic matter as food for them than in reducing export of random organics that can have a variety of undesirable properties, from yellowing the water to being toxic.

I had fought off Dino’s about 7 months ago by running uv. Dosing mb7. And running GAC things were great for about a month. I stopped dosing mb7 but continued to use uv and GAC. I battled low nutrients but when I added n & P I would get cyano or gha. I than would have to go back to using mb7 to outcompete the algae’s . I find it hard to believe the water quality is “dirty” as I’ve been doing lots of water changes and running a protein skimmer. Dosing mb7. And running Fresh GAC (changing about every 2 weeks).
My next step is to only run the skimmer at night, remove the GAC and stop dosing MB7. Acros seem happy but lps just seem to be starving.
My thoughts are that the GAC and over skimming is starving heterotrophic bacteria and they die out and aren’t able to compete with cyano when my nutrients start building up.