wood
Actually driftwood is wood, and petrified wood is a rock. lol Really. In becoming petrified minerals replace the wood as it decays. And you are left with a rock in the shape of the original wood. More or less. Same basic way fossils form.
Driftwood is a nice addition for most tanks, but you need to get suitable wood. Avoid pine or any soft wood. They will leach nasty stuff into the water. Also do not use grapevine or grape wood. It is found in pet stores for reptiles and birds. Also bad for the tank water. Malasian driftwood is ideal, but sometypes of native hardwoods are good. Maybe someone with more knowledge can tell you which is good.
If you add wood it may relaese tanins into the water, giving it a slight tea color. This is harmless and can even be athestically pleasing. Or not. lol Soaking the wood in water (outside the tank) for a few days to a few weeks before putting in the tank will help reduce this. Also boiling the piece for 15 min or so will get a lot of the tanin out. And serves to kill any unwanted hitchhikers on the wood. If your piece will not sink imediately, the soaking will waterlog it, or you can weight it down in the tank. Another advantage of the malasian wood is it will sink right away.
As for your fish needing wood, maybe. I have no experience with farlowellas so if some one else has....... As for your pleco, what species is it?? Most small plecos such as bristlenose, clown, and I think rubberlip do need wood in their tank. In the wild they scrape or rasp food off of wood and in the process injest small bits of wood. So they need to rasp wood. Sort of like metamucil max. lol I don't think the larger plecos, that are not panaques, need wood. Again if someone else can help?
And I just got a look at the size of this. Man, it is surprising what a little, okay, a lot on Mountain Dew will accomplish!! lol Hope this helps, if you are still awake, anyway. Good luck!!
