How soon after adding carbon can I switch meds, please?

[HappyFace]

I added the wrong medication to my tank (malachite formalin). One of my discus has gotten real sick so I want to put some new carbon in my sump to remove the med so I can switch medications to Metronidazole asap. How long does the carbon need to be in the tank before I can remove it and add the new medication?

My pump is a Jebao DCT15000 set to highest power 3962 GPH.

For anyone who might find themselves with lose activated carbon and nothing whatsoever to put it in, see attached pics. I was going to put it in filter socks but thought this would work better. I'm going to change out the filter socks underneath right now.

[HappyFace]

I'm guessing it's already gone from my water now I'm just waiting for it to process out of the fish. I was looking up half life of malachite green and formalin and I found this: "Malachite green was rapidly absorbed and concentrated in the tissues during waterborne exposure. The rate of accumulation was directly related to pH of the exposure water. After waterborne exposure, elimination of the parent compound from plasma also was triphasic with a terminal half-life of 4.7 hr."

link below
https://pubchem.ncbi.nlm.nih.gov/compound/malachite_green#section=MeSH-Pharmacological-Classification
see heading 9.2 Absorption, Distribution and Excretion

and this: Formaldehyde is absorbed rapidly and almost completely from the rodent intestinal tract. In rats, about 40% of an oral dose of (14)C-formaldehyde (7 mg/kg) was eliminated as (14)C-carbon dioxide within 12 hours." 10% remains inside their body after 4 days

link below
https://pubchem.ncbi.nlm.nih.gov/compound/712
see heading 10.4 Absorption, Distribution and Excretion

So I'm guessing it should be safe to administer Metro 12-14 hours after putting the activated carbon in the sump?

[HappyFace]

Apparently I have the patience of a 3 year old with a bag of candy set in front of him. My fish are dying and I can't handle doing nothing. One of my cories died abour an hour ago.

I let the carbon run for 3 hours total. The tank is crystal clear. It's been clear all day though since some of the water was changed out. I put their plastic Rocks back in so they can feel more comfortable and added metronidazole. Blondie (my old yellow girl) has bad equalibrium and looks awful. Boo-boo is blind. It's been about 20 minutes since I added the metro. The 3 discus stopped sloughing their slime coat in that time. So far everyone seems ok with the metro.

[Willie]

Unless that's a micron mesh filter sock, you may have micro particulates of activated carbon still in the water. They won't harm the fish, but can still absorb medication like metro. I'd recommend a large water change before re-medicating.

Willie

[HappyFace]

Unless that's a micron mesh filter sock, you may have micro particulates of activated carbon still in the water. They won't harm the fish, but can still absorb medication like metro. I'd recommend a large water change before re-medicating.

Willie

Thank you Willie. It's not a Micron mesh sock but I just read that Micron mesh is 200 microns and that's exactly what my filter sock is so has the same capacity for filtration.

[Willie]

I was thinking about a 10 micron pore size mesh, which is typically what you get with a paper-based filter used ahead of water purification systems. As a basis of comparison, a bacterium would have a diameter of 1 micron. The old diatomaceous earth filters would take out stuff even smaller than that. But no harm...

Willie

[HappyFace]

I was thinking about a 10 micron pore size mesh, which is typically what you get with a paper-based filter used ahead of water purification systems. As a basis of comparison, a bacterium would have a diameter of 1 micron. The old diatomaceous earth filters would take out stuff even smaller than that. But no harm...

Willie

That's terrible. Why do they only sell activated carbon filter bags that are 1-2mm? My 200 micron bag is 5-10 times smaller holes than that! Everyone using carbon has tons of carbon in their tank! I wonder if that affects things like nutrient absorption.