How to Fix Brown Algae on New Driftwood in Aquariums
You carefully selected a beautiful piece of driftwood, soaked it for days and positioned it perfectly in your tank. Two weeks later, it is coated in a slimy brown film. Frustrating, but entirely normal. If you want to fix brown algae on new driftwood in your aquarium, this guide from Gensou Aquascaping at 5 Everton Park, Singapore explains what is actually happening and how to resolve it quickly.
What the Brown Film Actually Is
The brown coating on new driftwood is usually not algae at all. It is a bacterial biofilm that forms as microorganisms begin breaking down organic compounds leaching from the wood. Diatoms (true brown algae) may also appear alongside the biofilm, particularly in newly set up tanks where silicates are still present in the water. Both are harmless and temporary, though they look unpleasant.
The biofilm phase typically lasts two to six weeks depending on the wood species and how thoroughly it was pre-soaked. Mopani, Malaysian driftwood and spider wood are especially prone to heavy biofilm production.
Let the Cleanup Crew Handle It
The most effortless solution is biological. Otocinclus catfish, nerite snails and Amano shrimp (Caridina multidentata) devour bacterial biofilm enthusiastically. A group of three otocinclus can strip a 30 cm piece of driftwood clean within days. Nerite snails work more slowly but methodically, leaving clean trails across the wood surface.
If your tank is newly cycled, wait until the nitrogen cycle is established before adding sensitive fish like otocinclus. Nerite snails and Amano shrimp are hardier early additions that tolerate minor parameter fluctuations.
Manual Removal Methods
For immediate results, remove the driftwood and scrub it under running water with a stiff brush. An old toothbrush works for intricate textures and crevices. Avoid soap or detergent. Return the wood to the tank and the biofilm will regrow, but each cycle is lighter than the last as the leachable organics diminish.
A turkey baster or small powerhead directed at the biofilm during water changes dislodges loose material that the filter can then remove. Siphon debris directly from the wood surface while draining water.
Pre-Soaking to Reduce Biofilm
Thorough pre-soaking dramatically reduces biofilm intensity once the wood enters your display tank. Soak new driftwood in a bucket of warm water for one to two weeks, changing the water daily. This leaches out tannins, dissolved organics and surface compounds that bacteria feed on. Spider wood, which is notoriously messy, benefits from boiling for 30-60 minutes before soaking if the piece fits in a large pot.
In Singapore’s warm climate, soaking water turns dark brown quickly. Change it as soon as it discolours heavily. The warmer the water, the faster the leaching process completes.
Addressing True Brown Algae (Diatoms)
If the brown coating persists beyond six weeks and has a gritty, powdery texture rather than a slimy one, you are likely dealing with diatoms rather than biofilm. Diatoms thrive on silicates and are common in new tanks using fresh substrate or tap water with elevated silicate levels. They resolve naturally as silicates are consumed, usually within two to three months of tank setup.
Nerite snails are the most effective diatom eaters available. Two or three nerites in a 60-litre tank keep diatoms under control while the tank matures. Increasing light intensity does not help with diatoms and may invite green algae instead.
When to Be Concerned
Brown biofilm on new driftwood is cosmetic, not harmful. It does not affect water quality, fish health or plant growth. The only situation warranting concern is if the wood itself begins to deteriorate, turning mushy or producing a foul smell. This indicates the wood is decomposing rather than simply leaching. Soft, rotten wood should be removed immediately, as it can crash water quality. Quality hardwood driftwood purchased from reputable aquarium suppliers should not have this problem.
Patience Pays Off
In most cases, the brown film resolves entirely within four to eight weeks without any intervention. Combining a cleanup crew with pre-soaking and occasional manual scrubbing accelerates the process. Every piece of driftwood goes through this phase, and experienced hobbyists in Singapore treat it as a routine part of setting up a new aquascape rather than a crisis. Once the biofilm phase passes, the wood develops a beautiful aged patina that only improves over time.
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emilynakatani
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