Charcoal as a media

[Paul Letby]

Hey guys, I'm going to open this up for debate, as things are getting a little off topic on my personal system discussion.  There have been questions as to the safety of charcoal as a media, and I'm sure there are questions out there regarding it's environmental impact.  So let's let fly with the questions and hash this out.  I'm definitely not the expert here, and I am hoping George will weigh in on the issues. 

 

Personally I decided to use charcoal based on the fact that I have free access to wood, and needed a cheap and light media for use in a GB supported by a light stand that's not meant to support a lot of weight.  I know that activated charcoal is used in aquaria as a filter media, so I'm pretty sure it's safe.  That said we all know that many things from tropical fishkeeping don't transfer to aquaponics very well.

[Vlad Jovanovic]

@Bob...Like Jesse says, ash content will certainly affect pH values (obviously), and again, this is mostly related to the pyrolysis temps used. Acid washes are used to partially remove this ash content (inorganic Mg and K) which plug up all those small pores...

[Jon Parr]

Of course ash will raise, and unburnt wood lowers, but in a retort there is no ash (or unburnt wood, ideally), just char. Remember, it isn't burnt wood, it's baked wood. Imagine Cajun blackened fish, only instead of fish, it's wood. I don't know how it affects pH directly, I haven't tried it, and unfortunately I don't have any fresh char at the moment to experiment. I would imagine that good clean char from a retort would be pretty neutral, no ash or tannins.
Now, char made in a TLUD would be ashy, fo sho

Jessie, nice site. So how about that advice...Pretty please?