Algae ID.

It's not algae... It's bacteria, and it's harmless. Some fish and definitely snails will eat it happily. You make a real mess trying to remove it. So just let it be. It will go away.


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I've never seen white algae... It photosynthesizes, so I don't think it can be white. Macro bacteria can appear at any time, but typically I've only seen it when putting something new in the aquarium. It is possible that it reappeared on the dried driftwood because you "made it new" by drying it out. If it starts spreading around the tank on its own, then you might need to pay it more attention, but I'd be willing to bet it will "disappear" on its own over time or by being consumed by an aquatic creature in your tank.

To your question about drying it in the oven... Unless you have a kiln, your oven doesn't get hot enough to dry it completely and that might start a fire. It is not suggested.

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It looks like black beard algae to me.
This is not a fun one to deal with and can take some time to clear up.

I also think that is brush algae (aka beard algae). The photo may be misleading in colour, as I would suspect the algae is more dark green than it appears here. BTW, just for the record, if it were a white fungus...some of this is safe, but some is deadly toxic.

Algae of some form is going to be present in every fish tank. It is impossible to keep a fish aquarium completely free of algae; such a tank would not be biologically balanced or healthy. The only detriment from algae is if it begins to affect plant growth (if there are live plants) and we aim to control this. But on its own, algae serves a function much the same a splants, in removing organics and producing oxygen. The wood in my tanks is covered in brush/beard algae, but it stays off the plant leaves provided I keep the balance biologically. Even if you were to somehow kill all the algae on that chunk of wood, placing the wood in an aquarium would inevitably cause new algae to appear.

Byron.

I get that whenever I trim my echinodorus cordifolius. It grows on the stem below where I trimmed it. My otos quickly eat it off once they find it though. Interestingly this is the only place I've seen it grow in my tank, no other plants or DW. I believe this is a fungus. I once took a picture of it, I'll post it if I find it.

I'd get rid if the wood. The fungus, if that's what it is, must like it as a food source. And that means fungus will be around for a long time feeding off of that wood. Once my otos eat the dead plant matter, the fungus is gone/dormant in my tank.

Hard to see but here's the picture I took in my tank. It's growing on the decaying stub on the lower left.