Driftwood floats because it's less dense than water, so you need to weigh it down or attach it until it becomes waterlogged enough to sink on its own
New driftwood floats. The wood hasn't absorbed enough water yet to become denser than the surrounding tank water, so it will bob to the surface no matter how hard you try to push it down. You have three practical routes: anchor it with weights, tie it down with fishing line or thread, or let it soak in a separate container until it sinks naturally. Which method you choose depends on how long you want to wait, what your tank setup looks like, and whether you mind visible anchoring materials.
The timeline matters. Driftwood can take anywhere from a few days to several weeks to become fully waterlogged, depending on the wood's density, thickness, and how much surface area is exposed to water. Heavier, denser woods sink faster than light, porous pieces. If you're willing to wait, soaking it outside the tank is the cleanest option. If you need it in place now, anchoring or tying it down works when ready.
Key Takeaways
- Driftwood floats until it absorbs enough water to become denser than the tank water, a process that takes days to weeks depending on wood type and thickness.
- Weights like rocks, aquarium-safe lead strips, or stainless steel weights can hold driftwood down without damaging the wood or harming fish.
- Fishing line, thread, or plant weights can tie driftwood to rocks or tank equipment, and the line becomes invisible once algae and biofilm grow on it.
- Pre-soaking driftwood in a bucket or separate container before adding it to the tank eliminates the floating problem but requires patience and extra space.
- Boiling driftwood speeds up water absorption and also removes tannins that cloud tank water, though it doesn't may provide the wood will sink when ready.
Using weights to hold driftwood in place
The simplest method is to place a weight on top of or beside the driftwood to push it down. Smooth rocks from outside work, but aquarium-specific weights are safer because they won't leach minerals or chemicals into your water. Stainless steel weights, lead-free aquarium weights, and even stainless steel fishing sinkers are all options. Avoid painted rocks, treated wood, or anything with a coating, since those can break down and cloud your water or harm fish.
Position the weight so it doesn't look like an afterthought. Lean the driftwood against a rock formation so the weight becomes part of the landscape, or place it underneath a hollow section of the wood. The weight needs to stay in contact with the driftwood to be effective — if the wood shifts, the weight can roll away. Check the setup after a few days to make sure everything is still in place and the driftwood hasn't started to float up at the edges.
This method works best for smaller pieces of driftwood or for wood that's already fairly dense. Very light, porous wood might need multiple weights or a combination of this method with another anchoring technique. The advantage is that weights are invisible once the wood settles and algae begins to grow on the tank bottom.
Tying driftwood down with fishing line or thread
Fishing line is nearly invisible underwater and won't harm fish or plants. Use clear monofilament line in a weight that matches your tank size — 10 to 20 pound test is standard for most home aquariums. Tie one end of the line to the driftwood, then tie the other end to a rock, piece of equipment, or the tank frame itself. Make sure the knots are tight; driftwood will test them as it tries to float upward.
The line becomes completely hidden within a few weeks as algae, biofilm, and plant growth cover it. This method works for larger pieces that are too heavy to move easily and for wood you want to position at a specific angle. You can also use black thread instead of fishing line if you prefer — it's thinner and even less visible, though it's more fragile and may need replacing if fish or plants damage it.
Tie the line so it doesn't cross the open water where fish swim. Route it along the back of the tank or through plants and rocks so it blends into the landscape. Avoid tying it so tightly that you bend or crack the wood — driftwood is brittle and can split under pressure. Leave a tiny bit of slack so the wood can settle naturally as it absorbs water.
Pre-soaking driftwood before adding it to the tank
The most reliable way to avoid floating altogether is to soak the driftwood in a bucket, tub, or separate container of water for several days or weeks before putting it in your aquarium. Fill a container large enough to submerge the wood completely, and change the water every few days. This speeds up water absorption and also removes tannins — the brown compounds that leach from fresh driftwood and cloud your tank water.
How long you soak depends on the wood's size and density. Small, thin pieces may sink after three to five days. Large, dense pieces can take two to four weeks or longer. You'll know it's ready when you place it in a bucket of fresh water and it sinks to the bottom on its own without floating back up. Test it a few times over several days to be sure.
This method requires space and patience, but it solves the floating problem completely and also clears most of the tannin discoloration before the wood enters your tank. If you have the time and a place to store a soaking bucket, it's the cleanest solution. Many aquarium keepers soak new driftwood while they're cycling a new tank or preparing it for fish.
Boiling driftwood to speed up sinking and remove tannins
Boiling driftwood in a large pot accelerates water absorption and removes tannins faster than cold soaking. Bring a pot of water to a rolling boil, add the driftwood, and let it boil for 10 to 15 minutes. Remove it carefully with tongs and let it cool completely before handling. Boiling doesn't may provide the wood will sink when ready, but it does soften the wood fibers and help them absorb water more quickly.
After boiling, soak the wood in fresh water for at least a few days before adding it to the tank. The boiling step cuts down the total soaking time significantly — wood that might take three weeks to sink on its own can often be ready in five to seven days after boiling. This is useful if you're on a timeline but still want to avoid anchoring methods.
Be cautious with very small or delicate pieces — boiling can make them brittle or cause them to crack. Large, dense pieces handle boiling well. Use a pot you don't cook food in, or use a dedicated aquarium pot, since driftwood can stain cookware. The water will turn brown; that's normal and expected.
Combining methods for stubborn pieces
Some driftwood is so light and porous that a single method won't hold it down. In these cases, combine techniques: use a weight underneath and tie the wood down with fishing line at the same time. This double-anchoring approach works for very buoyant pieces or for wood you want to position in a specific way that a single weight can't achieve.
You can also soak the wood while it's weighted in the tank. Place a weight on top of it and let it sit for a week or two while it absorbs water. Once it becomes denser, you can remove the weight and the wood will stay down. This hybrid approach lets you have the driftwood in your tank when ready while still letting it waterlog naturally.
Monitor the wood for the first week or two after you add it. If it's still trying to float despite your anchoring, add another weight or tie it down more securely. Once the wood has absorbed enough water, it will stay in place on its own and you can remove the weights or line if you want.
Preventing tannin staining while anchoring driftwood
Fresh driftwood releases tannins into the water, turning it brown or tea-colored. Anchoring the wood doesn't stop this — it just keeps the wood in place while it stains your water. To minimize tannin release, soak or boil the wood before adding it to the tank, or do frequent water changes during the first week after adding it.
Activated carbon in your filter removes tannins quickly. If you have a filter with a media basket, add a small bag of aquarium-grade activated carbon and replace it every few days until the water clears. This is faster than waiting for tannins to fade on their own, which can take a week or more depending on the wood and tank size.
Some aquarium keepers accept the brown water as temporary and do nothing. Tannins are not harmful to fish or plants — they're just a cosmetic issue. The water will clear naturally as the wood finishes releasing tannins and as you do regular water changes. If you prefer clear water when ready, activated carbon is the fastest fix.
Frequently Asked Questions
How long does driftwood take to sink on its own?
It depends on the wood's density and thickness. Light, porous pieces can sink in three to seven days. Dense, thick pieces may take two to four weeks or longer. Boiling the wood first cuts this time significantly. Testing it in a bucket of fresh water tells you when it's ready — if it sinks and stays down, it's waterlogged enough for your tank.
Will driftwood eventually sink without any anchoring?
Yes, eventually. Once the wood absorbs enough water, it becomes denser than the tank water and sinks naturally. The timeline varies widely, but most driftwood sinks within a few weeks if left alone. If you don't want to wait, anchoring or pre-soaking speeds up the process.
Can I use regular rocks from outside to weigh down driftwood?
Smooth rocks work, but they can leach minerals or harbor bacteria. Aquarium-specific weights or stainless steel sinkers are safer because they won't break down or affect water chemistry. If you use outdoor rocks, rinse them thoroughly and boil them first to kill any pathogens.
Does boiling driftwood make it safe for fish?
Boiling removes surface bacteria and speeds up water absorption, but it doesn't sterilize the wood completely. Let boiled driftwood cool completely before handling, and soak it in fresh water for a few days afterward. This is safe for fish — boiling is a standard preparation step for aquarium driftwood.
What's the best way to hide fishing line tied around driftwood?
Route the line along the back of the tank or through plants and rocks so it blends into the landscape. Algae and biofilm will cover the line within a few weeks, making it invisible. Use clear monofilament line rather than colored line, and keep the line tight so it doesn't sag visibly across open water.