# Type of woods that are safe for the aquarium?



## AWolf (Jun 13, 2014)

Kegan Clark said:


> I recently got this dead Malus Halliana bonsai tree that my dad killed and decided to use it to make an aquarium moss tree.
> I was wondering if anyone knew about whether or not this tree releases toxins into the water which might harm CRS?


Your tree is a type of crab apple, which would fall into the 'fruit tree' category of hardwoods. You will need to take it out and clean it often, because it will rot and stink up your tank. How much it rots, and how fast is anyone's guess. You may be able to keep it for a long time, or it may get nasty in a short time. Keep an eye/nose on it. I'm going to paste this blurb:
'The reason why we do not use forest wood is that bogwood has been 'preserved' by acids for millenia.it''s fairly to say that true bogwood is wood on it's way to become a fossil. as a result, it merely falls apart (or gets eaten by pleco's) but it doesn't pollute the tank fresh wood however rots and rotting fouls the water badly, making it unhealthy for fish 
now some fresh woods rot very very slowly; these are the ones we call 'hard woods" for that reason.
they are also very hard and difficult to use, you'd need more muscle- or toolpower.
these are to a certain degree useable for tanks.
common and useful hardwoods include beech, oak and fruit trees (cherry, apple, pear). a few other hardwoods are tropical; like mangrove (available in the shops) and mopani (a very hard wood) 
apart from those, most 'fresh forest' woods are best avoided!
anything from the connifer family is unusable: pine, larks, sequoia, xmas tree etc. all these contain turpentine or similar chemicals, which are bad for fish. walnut and trees from the almond family (including apricot and peach!) are quite toxic and a piece of wood from these will kill all the fish in a short time soft woods like willow, birch and the like are harmless, but they rot fast and pollute the tank.
rotting process uses a LOT of oxygen (the bacteria needed for rotting gobble it up), it also creates a LOT of nutriets on which massive algae blooms can grow.
we don't want that in our tanks that's why we go to the shop or to the nearest peat-bog to get our wood...'


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## Kegan Clark (Mar 17, 2016)

Thanks, that's very helpful. I'll keep an eye on it. Hopefully it works, because it looks awesome =(


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## frog111 (Feb 13, 2006)

What about mulberry? I have what I assume is a mulberry stump, that I recovered from the desert area near my home. The tree was cut down years and years ago, and the stump was pulled up. The wood is rock hard having weathered in the desert. It floated originally, and I added large slate bases to it, and it has been in use now for 15 years. No rotting, no foul smell.


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## PlantedRich (Jul 21, 2010)

As I read a lot of the info on what woods to use, it always strikes me that each is written with the degree and type of experience of that particular writer. Many times the information will vary from article to article due to different levels and types of experience. And many times my experience with wood is different. That is the case with much of the info in the above blog reference. I find a lot of difference in my wood use so here is my spin on the subject. 
I find wood is made up several different things we might call soft parts. Sap, tannin, moisture are all different names for the soft parts, maybe? Then there are the hard parts and those are different levels of hardness. Bark and solid wood? I find the bark has lots of the soft wet stuff while the solid wood starts out with lots of those but once totally dry there is only hard cellulose left. 
I find that I can avoid the trauma of tannins, toxins and much of the other bad stuff if I avoid the wet items (sap, tannin, moisture?) by only using fully dry wood. Doing this lets me use many of the woods which the writer above says can't be used. One often mentioned as unusable is cedar or any of the "softwoods". 
I can see how it would be easy to confuse using green cedar which still has moisture embedded with something that would be totally unusable. Cedar is one which is also famous for holding the moisture so it might be easy to say it never dries out. That is why it is handy for use like decks and fences where we want to have the moisture and toxins to prevent bugs and rot. But it is not true that cedar never dries. It just takes a lot longer so that a lot of people may say it never does. 
Part of the confusion may also come from the way wood works differently in different water. 
I think we can pretty much agree that water that has low GH and KH for buffering the PH will be easy to create wild swings in the parameters while it is much harder in high GH/KH due to the buffering. So I can see that if you use a piece of cedar that is not quite dry in soft, acidic water you will get a much larger change than if you use a really dry piece in hard alkaline water. I see the wood as being only part of the question and the water as the second part. But then much of the information is written as if all water is the same. Those who would say plants won't grow in hard, alkaline water should take a look at a spring branch in limestone country. There are tons of plants growing in those places. Springs in Florida for example? 
I use fully, totally dry cedar/juniper wood all the time in my tanks of hard alkaline water and see no change that I can measure. So before making blanket statements of what wood can/can't be used, I feel it is important to look at the WHY of things as well as WHAT is used. 

Using semi-dried wood in soft water is likely to have some degree of problems. The bark is one place where lots of tannin is found. 
I find that when there is a problem with wood it may not be the wood at fault but the water which doesn't have the correct level of buffering to prevent the problem. Just as we sometimes need to match the plants and fish to the water we use, we also need to do some looking to match the wood we use to that water.


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