Activated charcoal effectiveness and longevity experiment

[scardall]

If a significant portion of the capacity is being taken up before bacteria coat it, yes. If not, then no, or not much. .

Good point Randy. Question does flow rate/packing density in a reactor affect (contact time to full bacterial coating), If so what would you recommend to increase usable use time of the carbon? Thanks

 

[Randy Holmes-Farley Verified Community Expert]

Good flow might make it more likely to get saturated with organics before it became overrun with bacteria.

 

[Orm Embar]

Well, a picture taken today has a greenish hue. Replaced midnight 7/21, so that's 2 days. I will check it again tomorrow, and if it still looks "not bluish/clear" then I will massage the bag again. If the water is coloring up again this quickly, that makes me think that the carbon's adsorbing capacity has been reached rather than bacterial coatings/slime preventing further binding. If so, I may well go out and try some Purigen to see how long that lasts (I don't like the idea of bleach recharging, but I also don't like the idea of changing carbon on a less than weekly basis).

Another question that I simply don't have an answer to - what exactly am I trying to do? If my goal is to have continuously optically bluish/clear water with no yellowing agents, then my use of activated charcoal doesn't seem to be working the way that I would like it to (monthly changing of a reasonably cheap amount). If it's to remove soft coral organic compounds to try to protect my LPS corals (and my few SPS), then I don't have a good way of judging that short of chromatography/mass spectrometry that I can think of (and I have no access to either of those, nor do I wish to pay for someone to run samples). Argh . . .

On the other hand, I could simply add activated charcoal on a biweekly (every 2 weeks) or even monthly basis if I just wanted to ensure that soft coral organics didn't simply continue to escalate (again, assuming that yellowing agent removal parallels removal of those which may well be inaccurate as above).

Considering that, per BRS' video of yellowing rich water blocking up to 25% of PAR, I wonder how many tanks out there could be run just as successfully with less lighting if the water remained free of yellowing compounds. More assumptions (that once the water looks yellowish, you're getting the full 25% reduction rather than gradually worsening light penetration as levels continue to climb), but still food for thought.

 

[Orm Embar]

I'll post pictures tomorrow or Tuesday.

 

[Orm Embar]

Pictures for the past 4 days - 150 mL Rox (half of the usual dose), added to tank midnight 7/21; white balance roughly 3K using ProCamera (off of a paper towel) with similar lighting.

This looks like it is lasting for a much shorter period of time, which makes me think that the carbon is exhausted rather than clogged with bacterial overgrowth.

I will try the "bag massage" and see how things are tomorrow. Update - bag "massaged" to try to break up any clumps and to expose as much new surface area as possible. Rinsed under tap water (2nd time; first time was before initial use), clear runoff, replaced in sump.

 

[Orm Embar]

7/26 back to light blue/clear

 

[Forsaken77]

7/26 back to light blue/clear

What you could do is add multiple smaller bags of carbon instead of one bigger bag. That way you could be sure the carbon is exhausting all of it's usefulness before bacterial coating.

I actually put my bag of carbon near the output of my skimmer so it forces water through it. That's basically the same as "massaging" it.

 

[Orm Embar]

7/28 water still bluish/clear; bag massage 7/25 after that picture. I ended up buying some Purigen from the LFS; I will be trying that at some point as well.

If "massaging the bag" repeatedly (I don't have a skimmer so I don't have a high flow output besides the sump inflow which is where it is at the moment) is what is needed to get everything out of a batch of activated charcoal, I may end up buying a reactor to see if that makes it easier. Anyone use an AquaMaxx FR-M?

 

[Orm Embar]

7/30 still bluish-clear, on day 8. I'm not clear why the time to initial yellowing was so short before bag massage #1, but now it's lasting longer and we're now at day 8 with half of my prior activated charcoal dose and it's still working well. The prior dose (double current) lasted at most for 10 days (less, actually - I don't have a color match on days 8 or 9, but on day 10 the water was definitely yellowed despite bag massage).

So, if 300 mL activated charcoal was not working as of day #10 (9 day duration maximum), and 150 mL is still working well as of day 8, I'm expecting the charcoal to stop working for visible yellowing agents (and the water getting a yellow-brown tint as opposed to light blue) over the next 48 hours. If half the carbon lasts just as long, then the only explanations I can think of are that either Randy's prior comment about activated charcoal getting coated with bacteria/biofilms and not adsorbing the way it used to, the new bag is somehow affecting things (the new charcoal dose is in a 100 micron mesh bag, while previously charcoal was in the mesg bag that came with the Red Sea activated charocoal), or both.

I can't think of a reason that a 100 micron bag would cause carbon to last longer, unless it's acting as a mechanical barrier to bacteria getting inside the bag to colonize the charcoal. I may have to try the 300 mL dose again in the 100 micron bag to see how well that works. Having said that, a quick Googling of bacterial states that reef aquarium bacteria are generally 1 micron in size (Advanced Aquarist) so a 100 micron mesh doesn't sound like a particularly effective filter.

 

[hart24601]

Try the purigen?

 

[Orm Embar]

Day 16, 8/7 (today). Water still bluish to my surprise. The only different parameters are that the charcoal is in a 100 micron bag, some cespitularia frags are visibly growing, and chaeto growth in refugium. This is completely unexpected

 

[Orm Embar]

I have not tried Purigen yet. Once I figure out the specifics of the ROX gallon that I have, I will give it a try as I have a bottle of Purigen.

 

[TbyZ]

so, a coating of bacteria seems to inhibit carbons effectiveness in regards to adsoption.

So, how to best remove the bacteria coating without using a substance that the carbon may adsorb?

perhaps boiling the used carbon after a week of use. That would kill the bacteria. How effective would the carbon's adsorption potential be then?

 

[Orm Embar]

As of yesterday, my water color is still in the blue-green spectrum without visible yellowing (day 20). As this is so widely divergent from my first 2 runs, I'm not sure what to make of it. I also missed a week in there as I was out of town, so I have incomplete data. Having said that, in a skimmerless system, 150 mL ROX 0.8 in 32 gallons of display/43 gallons of system with a macroalgae (chaeto/dragon's breath) refugium is keeping my tank water without clear yellowing of the water after 20 days.

I'm now curious if the bag had anything to do with it, and will be replacing charcoal in my original bag when the water gets yellowed enough to see. I can't think of a reason why that would impact things.