I recently heard that Otocinclus should have a source of wood (such as
driftwood in the tank) as a dietary supplement.

Is this true?

My Ottos are doing fine, and I currently have no driftwood in the tank, just
a lot of algae. I have only had the Ottos in the tank for about three weeks
though.

It makes sense that wood might be necessary; the Amazon river is certainly
full of tree limbs and downed trees, but I had never heard this before.

The way I heard it, it was referred to as the "wood trick": you should have
a source of wood for healthy Ottos long term.