Spider wood is the pale, thin, root-like driftwood that branches out into fine tendrils, and it is one of the most-used woods in modern aquascaping. It suits the Nature Aquarium look because its branching reads as tree roots or bare winter growth at tank scale.
It will float at first
Spider wood is lightweight, so it will almost certainly float when it first goes in. This is normal and temporary, and it is the single thing most likely to catch out someone using it for the first time.
Two ways round it. Soak it in a bucket until it takes on enough water to sink on its own, or boil it, which does the same job faster. If you would rather not wait at all, weigh it down with stone until it waterlogs, which is the same trick used with other low-density woods.
Tannins and tinted water
All driftwood releases tannins, which tint the water an amber or tea colour. Spider wood is on the lower end for this compared with other aquarium driftwood, and a quick boil reduces it further while also helping the wood sink.
Whether you treat the tint as a problem is up to you. Filter media such as activated resins will clear it, or you can simply sit it out, since it fades as the wood exhausts. Plenty of aquascapers want the tint, and a blackwater biotope is built around it.
The white fuzz is normal
A harmless white biofilm commonly develops on spider wood during the first few weeks. It looks alarming, it is not a fungus attacking your tank, and it passes on its own as the wood settles. Shrimp and some fish will graze it. Removing the wood to scrub it does more harm than leaving it be.
Planting on it
The fine branching is ideal for epiphytes, which attach to surfaces instead of rooting in substrate. Tie or glue Java fern, Anubias or Java moss to the branches and let them take hold over a few weeks.
Keep the rhizome above the surface. Burying it is the most common way to kill an otherwise indestructible plant.
Spider wood questions
How long does spider wood take to sink?
It varies with the size and density of the piece. Soaking in a bucket works but can take a while, and boiling speeds it up considerably. Weighing it down with stone lets you set the scape up immediately while the wood waterlogs in place.
Should I remove the white fuzz on my spider wood?
No need. The white biofilm is harmless, common in the first few weeks, and clears on its own. Shrimp and some fish eat it.
Does spider wood lower pH?
Driftwood releases tannins and humic acids that can soften and slightly acidify water, though the effect is modest in a tank with regular water changes. Spider wood releases fewer tannins than other aquarium driftwood, so its influence is at the gentler end.