activated charcoal

[vertigo72]

Why arent we all using activated charcoal in our filters?

I just read on wikipedia that 1 gram of activated carbon has a surface area in excess of 500 m2. To put that in perspective, some of the best plastic biomedia has that much surface area if you have.. 500-1000 liters of it. Im guessing youd need ~2-5x as much of cut PVC pipes. Compared to one gram of activated charcoal!

Now surface area probably isnt the only thing that matters, but its pretty damn crucial for bio filtration and the difference is so immense, I wonder why we bother with plastics, when a small bucket of charcoal could do bio filtration far better than a garden full of 55 gallon filters?

Note: you would of course still need excellent mechanical filtration, just for breaking down toxics it seems nuts not to use some?

 

[jupiter1]

I think that for a gram of any media to have that much surface area the "structures" would be very very small . Problen here is cloging and diffeculty in rinsing . Those small structures would clog quickly and reduce the workig surface area , the area where the bugs are alive and working , to that of say a gram of pea gravel . Plastic media on the other hand does not clog as fast and is eaiser to rinse.

 

[vertigo72]

Im sure thats true, which probably is also why you need to replace activated carbon every 6 months or so (if not, then why?). And why I said, youd need excellent mechanical filtration to keep any particles away, as activated charbon wouldnt help one bit trapping those, and build up of muck would likely prevent it from working very fast.

Still, its not that expensive, replacing a bucket twice per year. And to prevent clogging of the entire filter, just put them in a moving bed with aeration?

Mind you, Im sure there is a reason its not used more frequently in ponds. Its not like its a new invention. Im just curious.

 

[jupiter1]

Nother wrong with exploring new ideas . If it were a practical lots of folks would be using it. I know from my fish tank days charcoal was to remove harmful impurities and to remove color from the water . Nothing like a fresh batch of charcoal to make the tank crystal clear .

 

[fishin4cars]

Vertigo, Charcoal would work, but it's similar to lava rock, It's so porous that the bacteria colonize and actually cover the charcoal making it useless for long term use as a biological filter media when packed in a filter.. I do use it but only as a polisher in the pond If you watch enough videos you'll eventually run up on those that use k1 or similar bio-fliter media that needs to be in suspension,(actively moving in the water column) They are designed to have huge growing surfaces for bacteria and yet not clog, Again like you said earlier in your post you would need good mechanical filtration before hand. I don't see why it couldn't be used as I have used it for years in my canister filter for my fish tanks, the biggest problem in a fish tank is the same thing, it's best if there is a second type of filtration going on so you can periodically change the charcoal out. Speaking of which, HMMMM, I think i need to go get some new for the fish tank, I don't remember the last time I swapped it out and I've been wondering why my water had a slight coloration to it!

 

[vertigo72]

Vertigo, Charcoal would work, but it's similar to lava rock, It's so porous that the bacteria colonize and actually cover the charcoal making it useless for long term use as a biological filter media when packed in a filter..

Thats why Id put them in a moving bed. Havent tried yet, but I think the floatation would allow it, given enough air. Anyway I tend to agree there is a reason its not more universally used. Unlike anoxic filtration, which is relatively 'new', or at least not broadly known, activated coal is among the best known ways to filter, so for sure it has been tried in koi ponds, and probably discarded. Still going to hang a bag in my last barrel, if it doesnt help, it probably wont hurt

 

[koiguy1969]

activated carbon and zeolite are both excellant chemical filters... zeolite can be rejuvinated easily by an overnight soak in a strong salt water solution and a good rinse,so you need not replace it.. zeolite absorbs and nuetralizes ammonias, and does it exceptionally well..., but 3 - 4 weks is the life expectancy of activated carbon @ 1/2 cup per 20 gals. i read a post,somewhere here that you can rejuenate activated carbon in an oven. contrary to that i read in an article that it cant be done outside a laboratory.

 

[vertigo72]

Yeah I think reactivating it in an oven is urban legend. if you read the proper procedure, it requires far higher temps and inert atmosphere. From wiki:

The most common regeneration technique employed in industrial processes is thermal regeneration.[17] The thermal regeneration process generally follows three steps [18]:

Adsorbent drying at approximately 105 °C
High temperature desorption and decomposition (500–900°C) under an inert atmosphere
Residual organic gasification by an oxidising gas (steam or carbon dioxide) at elevated temperatures (800°C)


Maybe someone only read the first line and thought it where 3 different ways to reactivate it, rather than 3 steps to take.

 

[Pond Boy]

It also starts breaking down releasing the natsies back into the water column.

 

[Spaceman]

It also starts breaking down releasing the natsies back into the water column.

Thats why Id put them in a moving bed. Havent tried yet, but I think the floatation would allow it, given enough air. Anyway I tend to agree there is a reason its not more universally used. Unlike anoxic filtration, which is relatively 'new', or at least not broadly known, activated coal is among the best known ways to filter, so for sure it has been tried in koi ponds, and probably discarded. Still going to hang a bag in my last barrel, if it doesnt help, it probably wont hurt

I am going to try making a charcoal filter using a 1' piece of 8" PVC pipe. With 1" fittings as inlet and outlet. A piece of fine mesh over the outlet should keep the pellets from escaping. By leaving 6' unfilled, there should be plenty of room for the pellets to move around.
Any comments?

 

[Meyer Jordan]

With the set-up you describe the pellets will congregate at the mesh outlet.There will be no movement. Moving bed filters have an open air surface with air typically forced in from below creating constant turbulence hence .. the moving bed.
Depending on water quality the charcoal will need replacing quite often if the removal of toxins is desired. As to its use as biofilter media, it is really a poor choice considering the rapid internal clogging of the inner particle voids which will result in anaerobic conditions.

 

[Spaceman]

With the set-up you describe the pellets will congregate at the mesh outlet.There will be no movement. Moving bed filters have an open air surface with air typically forced in from below creating constant turbulence hence .. the moving bed.
Depending on water quality the charcoal will need replacing quite often if the removal of toxins is desired. As to its use as biofilter media, it is really a poor choice considering the rapid internal clogging of the inner particle voids which will result in anaerobic conditions.

Update on the homemade charcoal filter I described. Upon checking at the local True Value store, I found a 2' piece of 3" PVC. I bought that and 2 caps. I drilled about 50 7/64" holes in one cap. My spare pump has a 1-1/4" pipe thread for the outlet. I made a hole in the other cap large enough to accept a 1-1/4" plastic pipe coupling. I cut the end off a plastic cap with pipe threads and used this to make a bulkhead connecter. I attached the assembly to the pump and added 4 cups of charcoal pellets. When I plugged it in, the water flow was nicely dispersed. I am assuming that the carbon pellets are swirling around at random, thus keeping them from being coated and sealing up.
After thinking about it a while, I am guessing that the pellets will eventually scour against one another until they wear away and pass through the small holes. I am hopeful that they will then just settle to the bottom or be collected in the pressure filter.
Since I added carbon to the system I am seeing a lot of small froth that finds its way into the skimmer. Is it likely that the carbon is taking out most of the natural mineral in the water and rendering the water more "soft"?