growing mediums

[bruce]

Has anybody ever used or know anythng about whether charcoal can be used as a growing medium?

[badflash]

I don't think it would be a good idea as it breaks down and crumbles too easily. I've not used it, but I think it would much up the works. Pea gravel works well.

[urbanrunoff]

i'm pretty sure charcoal would filter out some of the nutrients and are not a good choice.
pea gravel is nice but the ones from home depot are very "dirty" and need to be rinsed for a long time.
I mixed pea gravel and river pebbles

[bruce]

ok thanks

[jackalope]

Activted Charcoal would probably be OK, since it's used in aquariums for getting rid of ammonia and other things ..... that said, unless you have a place where you can buy it very cheap, it would be cost prohibitive, and it would need to be changed often or it would start giving off the ammonia, etc. that it had filtered ..... I'm for peat (if you need the acid in your system), pea gravel or expanded clay balls ..... not charcoal!

[ASIAquaticBio]

I think that the use of charcoal or bio-char might have some potential, but it would need some experimentation. The suitability of charcoal as growing medium will really depend on how it is produced. Charcoal as a structure has an excellent moisture holding capacity, has an open pore structure easily colonized by numerous beneficial microbes and mycorrhizae, has a CEC potential capable of capturing available nutrients from your water, and is also a great medium for your red earth worms. The challenge with any type of charcoal however is its relatively high Ph.

The Ph, availability of nutrients (N.P,K) from the original feedstock (material from which the charcoal or biochar is made), and the existence of any bio-oils (nutrient rich compounds concentrated in the charring process) is all contingent on the temperature and how long the charcoal is cooked.

Keeping your feedstock at 300 C for 2 hours will produce a product with excellent pore structure, moderate available nutrients (not so much that is would spike your system and cause algae blooms), and abundant bio-oils to stimulate beneficial microbe growth. As a rule chars cooked at lower temps will give you a Ph of ~8, which is quickly tempered and could be workable in an aquaponics scenario.

Chars cooked between 600-750 C (most commercially produced biochar and charcoal fall into this area) will generate a product with next to no available N,P,K , have no bio-oil, and will have a Ph between 10.5-11. These would likely be unsuitable as an aquaponics medium.

I would love to do some experimenting with char products as a medium and believe it has vast potential both in large scale operations and as a readily accessible medium in developing countries. In addition to its excellent structural and chemical properties, biochar acts as a long term carbon sink and current studies are showing a growing role for it in terrestrial soil reclamation and building.

If and when I attempt to grow in biochar I will post my findings here!
Cheers
ASIAquaticBIo

[rfeiller]

welcome ASIAquaticbio to our forum and thanks for the info. where are you located? if you could go back to your avatar and introduce yourself.
thanks
rich