So I'm 5 minutes into this video



Is there any reason one couldn't use char chunks instead of a pea gravel type thing? Then after a couple years pitch that as fertilizer into the garden and replace it with more saved up char from your down draft stove? You know, hypothetically.

Landon Sunrich : Mostly I am repeating ideas I gleaned from other Permies Forum threads - filtered through decades of junk thoughts, but here is my $.02 -

I Think the generally preferred material- smooth surfaced pea gravel was selected in part to reduce microbial contamination, being repeatedly washed
by the water circulated through it ! While this material is micro pored it is inorganic and not a great host for pathogens

Because of the micro-pore sizes within the chunks of charcoal, which is organic and thus a better host, you have much more opportunity to harbor a pathogen

there. Lets see what others think !

For the good of the Craft ! Big AL

I've been thinking about using biochar for the medium in my media beds. Seems to me that it might be good as it has such a high surface area (I think hydroton and expanded shale do also, the usual media of choice) so it would have lots of habitat for the nitrosofiers and nitrifiers in the system, and so make a really good biofilter. I think, since pathogens tend to be anaerobes, that as long as you're careful with your DO levels, and make sure your system doesn't have any dead zones, that there isn't any reason why it should be a problem. As far as I know, biochar is pH neutral, which is one of the main things to worry about.

If nobody knows for sure, maybe we should try it and see how it works.

Charcoal has been used as an important part of fish filters for decades.
Not all microbes are bad microbes. In fact you want a heathy makeup of microbes.
Now I am assuming you have a system to digest fish waste and/or trap and remove it.
Plants generally only take in what is soluble. So microbes play a key role in going from liquid and solid fish waste to NPK that plant roots take in.
Roots need oxygen so the warning about low disolved oxygen pockets in your system is valid.
Might want to spot check with a oxygen meter if you have one.
Can also use clean iron rods.
Will rust in water with oxygen. Will turn black in water with no oxygen. It is a old trick to see what soil does over a season.

Thanks all. I have no system, but when I set one up I want at least the chance of it being the best most innovative one around but right now I'm still in the research/hemorrhaging money phase of it all.

Also, Hydroton. I've seen people use this stuff. I don't really dig it. Looks like a high energy product to me. Like, it's basically popped rocks right? Like not the sugar/whey kind. The kind that involves way lots fire to make.

Just read an article on the this subject at Bright Agrotech. The author thinks it is a very bad idea, but the comments said otherwise, with caveats. The jist of it is that if you are insistent on using biochar in your aquaponics system, and it may still be a very bad idea, make sure it has been thoroughly saturated with nitrates so that it doesn't crash the system's nitrate levels.

Cool, thanks Andrew. Looks like a couple other people were thinking this one over right around the same time I we were here.

I find with my system over 5000 tilapia.Its best to try
experiment's with new ideas with just a few fish in a lil system and if it don't work I don't have much to loose ? I even use regular compost soil over gravel for certain plants in constant height beds loaded with redworms! Redworms r a must for me in non float raft beds. They keep solids broke down and airrate beds. And if they aren't happy plants won't b happy. Hope this might help you.