Backyard Aquaponics
A place to discuss aquaponics

This is kinda re-visiting an old topic that I had kinda let drop a while back but some question that Hadn't really gotten answered have started niggling me again.

This is wondering about using wood chips as media again. I started googlebutting around to see if I could find anything stating that particular wood types are toxic to particular or any fish.

What I've come up with is that most conifers (at least fresh) are not likely to be a good idea in aquariums. Boiled driftwood seems to be the best choice though it can leach tannins which might be unappealing to some people though they might be fine for many types of fish.

I learned that many fish need wood in their natural habitat!

Treated woods and creasote are bad for fish.

There is lots about fish eating wood debris from wood pulping plants and paper mills but it didn't seem clear how bad this was in some of the reports.

So, back to the issue of cypress. When I had asked about it, I was told not to use it in a system with fish but when I asked why, I was told that there are chemicals in it that will inhibit plant growth. I wasn't worried about the plants really since I had been using cypress mulch as media in Hydroponics systems and know of many other people who have done the same here in the SE USA. (This might all be because the cypress growing in swamps here is very different from cypress growing in AU.) Can anyone shed new light on this one?

Anyway, I wouldn't use cypress mulch now anyway as it isn't being very sustainably harvested as far as we can tell. This question is more of an academic question now.

What about other wood chips? (provided they are not treated with anything!) Anyone know of a reason not to use say Oak?

Here is the main reason I suspect that most people would want to stay away from most wood materials is that they will tend to leach tannins that will bring the pH down. What if bringing the pH down would actually be a good thing?

What sort of benefits/drawbacks do people see with what wood might leach into a system. I expect there may be some benefit in nutrients leached with the tannins and for fish that like blackwater it would probably be nice. What other points do people see and what types of wood might be good and what others might be bad?

I could get lots of nice big driftwood chunks from the place up in Michigan, most of it is quite old.

TC, I would think well aged drift wood would be okay, people use it in aquariums. I guess the issue would be determining if it has aged enough?

I personally wouldn't use anything else without at least doing some tests first - we had some tadpoles in a small pond that were growing quickly. When they started to grow legs we put a nice old dry peice of timber in the water so that the frogs had something to climb on when they were big enough. Overnight all of the tadpoles were dead Tannins, sap, whatever else leached out and was obviously toxic to the tadpoles.

Black Walnut is suppose to be deadly, even to livestock. Yew and Oleander are too. If you are really interested in wood chips/wood pulp, why don't you grow something like Papyrus and mulch it yourself. some pond people use straw hay bales to clarify water- part of it converts to hydrogen peroxide. But I think the biggest issue of any dead plant material, is that it will decompose in your system and create more oxygen depletion in your system. The reason being is that there is another bacteria that I have not heard discussed in this forum but it is called heterotophic bacteria, which a collection of different strains that do the same function. This aerobic (needs air) bacteria breaks down food particles and animal waste into ammonia, then the aerobic bacteria (Nitrosomonas) breaks down ammonia and convert it to nitrites. The aerobic bacteria (Nitrobacter) breaks down nitrites to nitrates which are non-toxic compounds for fish. As all bacteria within a good system are aerobic, high oxygen levels must be maintained throughout the system. This is a complete aerobic bacterial cycle. You get methane and hydrogen sulfide, from two other types of bacteria, when you end up with an unaerobic (no air) environment or dead zones within a system.

I know it doesn't take much to cause major frog kills. Are you certain the old timber had not been treated with something? Way back when they liked to use all sorts of nasty stuff on wood before they realized just how nasty it was.

I know that black walnut and several other related trees are capable of limiting competition from some other plants by the production of jungloe which inhibits many types of plant growth (though not all as there are some plants that can grow under a black walnut apparently.) I had not realized that the wood itself was poisonous. I do know about oleander. I also realize that the sap in most conifers would be best kept away from the Aquaponic system.

Definitely to keep in mind that any dead organic material in the system will produce more O2 demand as well as a likely increase in acidifying effects or a drop in pH. Another reason to have some worms living underwater in a system, handy way to know if O2 is staying high.

Another thing to keep in mind (this is from my soil gardening experience) any high carbon material introduced into a system is likely to lock up a bit of the available nitrogen to help speed it's decay process. Granted, anything decaying very quickly will in turn be releasing that nitrogen back into the system. If these are good or bad things seems to be up for debate.

Luckily, I have a handy test system that I can safely experiment on since there are no fish in it to kill!!!!!!! I have already added a bag of wood chips into the flush tank of the Pee Ponic system to see what effects might be observed.

i know that Jaymie might have something to contribute here..................


Also there was a member here (cant remember their name) but they used i think pine for their grow bed medium................killed two or three load of fish and then checked it in

Yep I'm sure, it was from a tree cut up by me and dried for more than 2 years...

TCL... David mentioned that he used wood chips (cypress) and they released a "red" dye colouring that the fish didn't like...

i.e they floated upside down...

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From memory, I think a lot of pinebark/cypress woodchips have been treated with chromated copper....

french oak ? ....

hehehe

what about pyrolized or charcoaled wood? would that create more surface area and remove all the sap issues?

I think part of my problem with woodchips is that they will eventually break down and you will have to reload the growbed with whatever you started with.

The coco coir that we used in 4 of the strawberry towers as an experiment has not worked well. Now it is starting to breakdown a bit, the ants carry it off, if for some reason the flow increases to that tower a lot washes out and is lost. We won't bother using it again. Once this lot is gone I'll fill those towers with gravel like the others.

Clean gravel is inert, once you've got it you are set

Copper doesnt kill fish

Agreed ,, but massive doses do.

Outback,
Kinda non-sequiter there?


Important not to use chips that are treated in any way. Died red, treated with fungiside etc.
Avoid woods with strong chemical properties, like conifers with their pitch, trees remarked for their ability to resist rotting, trees known to be poisonous, and trees known to inhibit the growth of other plants chemically.

Jaymie, thanks for sharing your results about the coir.

Anyone using wood as media in a system would need to replace it regularly. I definitely like gravel as media but I'm also curious and like to know the pros and cons of things so when the next group come along and want to try it, I can share the important points and let them decide with a little more information.

Sequine what ??

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