Charcoal - danger with age?

[Andyroo]

Good morning good & wise
and a Happiest of wishes for 2021!

Q: a couple of wide-yaps on ye ol'Facebook have suggested that charcoal gets old & toxic within a filter.
Yes? No? If yes, how&why?
The only reason I can imagine that it'd go "bad" would be if my tank was suffering a particular chemical load that would be collected by the Carbon, but then released again as the Carbon degrades. Yes? No? More?

Me, I don't know this & have never had an issue (that I know of). I've been using bagged local charcoal as course pre-filter for a few years (decade+), including a lovely chipped bamboo that's come into the markets more recently. This is in mondo-sumps on client ponds, as planter media and currently in my own 8Gal canister home-system. As bagged pre-filter I/we just shake the bags so the crud goes into the sponge, then clean the sponge with the hose or in the sea - depending on mood, weather and/or location.

I use at set-up in case there's residues from cement or epoxy/sealant/tanjit/chemical curing or Chlorene, depending on the fill-water source, then leave it as it's got a hell'of'a surface area & loads up with BB (I expect). After that first run-through I don't don't tend to change the charcoal, just top it up. If there's a specific polluting event like a flood or planter addition or rebuild, then we change out ~50% with new. The old goes to the orchids & cactus, who seem to appreciate it.

Thoughts, thinks or thunks?
with thanks

 

[A201]

I've never heard of aged filter charcoal becoming toxic. It does becomes ineffective over time.
I'd venture to say that the majority of experienced fish keepers only use carbon on a temporary basis, to remove meds or other impurities.

 

[TwoTankAmin]

This is basically another urban aquarium myth. When carbon becomes filled to capacity that is basically the end of it. It cannot hold anything more and it does not suddenly release it back into the water. What may happen is a tiny amount may let go and that means there is then a bit of space to adsorb other stuff. And this happens quickly.

Most of us have no idea of how to use carbon. The most important consideration is that it can reach it's useful capacity fairly rapidly. This can be is as little as 24-48 hours. How fast it reaches capacity will depend upon how much stuff is in the water for it to capture or detoxify. This is a pretty good explanation provided by Algone. This cmpany sells carbon for use in aquariuums.

Carbon is considered chemical filtration. The effectiveness of activated carbon is based on a three-step process. The first is adsorption. Static forces will attract particles adsorbing them onto the surface of the carbon. Bacteria that settle on the carbon surface will further consume the waste. Another process is the diffusion of gases. Absorbed into the carbon the gases are detoxified (i.e. Ozone O3 into oxygen O2). The third process is called chemosorption, where particles are irreversibly bound to the carbon.

Activated carbon removes organic pollutants, some of which discolor the water with a yellowish tint, organic acids, proteins, hormones, antibiotic compounds, and organic compounds as well as a variety of chemicals, medications, metals, and minerals.

Inorganic substances removed are, chlorine, chloramine, colors and odor causing substances such as phenols.

Removed organic, particles and substances adsorbed by the carbon will remain biologically active. Trapped waste particles will still decay and remain part of the aquatic system. Activated carbon is therefore best used on a short term basis and replaced regularly.

The quantity of carbon needed for an aquarium is about 3 tablespoons of carbon for each 50 Gallons of water. Carbon is quickly used up and can be removed after just 24-48 hours. If left in the system longer, it will no longer serve its purpose.

Once the activated carbon has been used up the re-release of the adsorbed substances back into the aquarium is minimal.

from https://www.algone.com/activated-carbon-and-chemical-aquarium-filtration

Bear in mind that carbon, like many things aquarium related, cannot be quantified universally. It should be used as needed. I happen to have very nice well water. I rarely need to use carbon. I keep a tea stained tanks and using carbon in them would remove the staining. I use carbon to remove medication from the water, I use it ti remove something non-lethal that may have accidentally gotten into a tank, I do not use it on a continuing basis. One way to extend the time between carbon changes would be to use more, For example, use 6 tablespoons per 50 gallons instead of 3.

Whether and when to use carbon in any tank is a function of the water quality in that tank. The most important factor is what is in one's tap or whatever water one may use. But even the best water can become not so good based on how we deal with a tank. If one is lazy and fails to do regular tank maintenance, you will have better odds of needing carbon. If you have to medicate a tank, you will likely need to use carbon afterwards. If you did not soak your new driftwood well enough, you may need to use carbon. If you overstock, you may need to use carbon.

The one thing that is sure is if you do use carbon there is no danger of it releasing "bad' back into the tank. You greatest risk is that your carbon will become filled to capacity and a failure to change it will mean the benefits of carbon are no longer there.

Another note, again from the Algone site. I would bet most of us do not do this, I don't and I actually have RO/DI water always available.

Carbon is an organic and all organics contain phosphates. During the manufacturing process, the carbon is often washed using phosphoric, hydrochlorid, or sulfuric acid, to remove inorganic and organic residues.

Acid washing and the removal of organic material will lessen the ash content as well as leachable phosphate. Washing carbon with phosphoric acid does not introduce phosphates.

Soaking the carbon prior to use in the aquarium will cause the phosphates and ash residues to leach out safely, therefore the phosphates will not be introduced to the aquatic system unknowingly.

Because of the ash and phosphate contents, it is advisable to soak the carbon in distilled or R/O water for a few days. It will not diminish the performance, but greatly reduce any possible and avoidable side effects.

I would also add that when carbon is used in large scale drinking water treatment plants, there is a greater danger that some substancs adsorbed can leach back out when the concentration of those substance is greatly reduced or removed from the inflowing water. However, the list of what is in the raw water coming in or what gets added to disinefect and otherwise treat water for drinking are not the same things as we get in our tanks. After all, what most of us use to fill our tanks is drinking water which has already been treated and which should not contain much we need to remove. Dechlor products tend to deal with any incoming chlorine or chloramine. Carbon could remove this stuff if we did not use chemical means to do this.

I hope this information helps.

 

[Andyroo]

Very helpful, thanks TwoTankAmin . Largely as expected and i'm glad to have it confirmed.
My current water is rain, as produced somewhere between here & Cuba (winter) or here & Venezuela, maybe St Lucia (summer) IE it's pretty clean barring whatever's accumulated on the roof: dust, leaves, soot, bird-poop etc. Not much & I don't get sick... at least not yet My primary pond-client's also on roof-rain, but he's by the sea so I do worry a bit about salt... likely not much of that, either, though. Worth noting that our roofs are aged zinc (galvanized steel) and not new zinc or cedar shake, both of which do carry risk.

I've liked charcoal as it's higher SA & lighter weight to move/carry than gravel & and stuff like pot-scrubbers are prohibitively costly around here. It's a headache early-on as it takes a while to sink, but so it goes. The chemical filtration element's a nice bonus, but not a primary consideration. I do pay attention to the tree sp. that it's coming from a some are toxic & may carry residues & some are endangered, whereas bamboo is invasive, common & clean. Check Annabel if you'd like to try: <http://kewparkfarms.com/bamboo-charcoal/> (please excuse the cheeky little plug for my neighbour's farm)

I'm currently coming through a cyanobacteria (blue-green algae) bloom and there's some internet writings that this can come from imbalances of insufficient Nitrogen, which may be related to this charcoal(?) so I'm actually looking forward to it loading-up. I'm vacuuming & tweaking light & adding plants & ramshorns, fish don't seem to care either way & injuries seem to clear up quickly (knock wood).

Thanks again. I'll not bother responding to FB, let them think they've won