To make driftwood sink (and not float) in an aquarium, you’ll have to hold it down until it’s completely saturated or put some extra weight on it. Boiling the piece of wood is also an acceptable alternative..
With that said, there are several ways you can hold or weigh down driftwood in a fish tank, most of which we shall discuss in the span of this article.
But first, you need to understand buoyancy in physics! A class is effectively in session, let me educate!
Buoyancy or upthrust, is an upward force exerted by a fluid that opposes the weight of an immersed object, in this case, driftwood, but I guess you already knew this.
Therefore, to sink your driftwood, you will want to make sure the weight of your wood is more compared to the upthrust exerted by the water column. And that is where the extra-weight, saturation, and anchoring comes in.
Read on for detailed hacks on how to keep your driftwood from floating.
How To Get Driftwood to Sink in a Fish Tank
It is not much of a hassle to sink driftwood, but it requires a commendable level of patience, and depending on the type of driftwood you have, more, than less resilience is best.
More porous wood soak up water faster and sink quickly, whereas less porous hardwoods take a little longer. However, some porous woods are usually lighter hence don’t descend all the way, meaning there are more likely to require extra-weights to hold them down.
Some kinds of wood are not really suitable for aquaria use because they are too buoyant, which is why Mopani and Malaysian driftwoods are common. Manzanita also works well because it readily becomes waterlogged; in a week or two.
For this reason, I recommend you start by soaking and boiling your driftwood, and if it does not sink, then weigh it down.
Does boiling make driftwood sink?
Boiling a piece of wood until it is waterlogged and sink on its own is most definitely a solution, albeit the need to have a huge pot to cover the whole.
Boiling, like soaking driftwood helps to leach tannins out of the wood as well, which can otherwise discolor your water and can be harmful to some fishes.
Plese note, that some tropical aquarium fish, particularly those from the Amazon ecosystem like tetras and angelfish, may prefer the weak-tea color of tannins in the tank.
The boiling process also sterilize and wipe out algal and fungal spores that may be hiding in the crevices of the driftwood, more so found wood.
How Long Should You Boil Driftwood
I recommend boiling a piece of driftwood you plan on putting inside a fish tank for 30 minutes to 2 hours, but if the piece of wood is too long to boil in a single go, your can turn it after a set period to cover both ends, meaning you will need double the time.
Once the whole piece has boiled, transfer it to a sink full of water to cool it then verify if it can sink. If the process does not work, you may want to consider weighing the driftwood down since it will be the more economical solution at that point.
How Long Does it Take Driftwood to Get Waterlogged?
Arguably, the easiest way to keep driftwood from floating is soaking the piece until it’s completely waterlogged.
But realistically, how long does it take till a piece of driftwood is waterlogged enough to sink on its own?
Well, in my honest opinion, it varies widely among different types of woods. Some woods may even never sink altogether unless you weigh them down.
That said, the average time it takes for most driftwoods to sink is anywhere between 2 days (for boiled, highly porous woods) to 2 weeks. It might take up to 4 weeks or even 2-months for less porous woods to sink.
Wood sinks when it becomes waterlogged, and the water replaces all the air trapped inside the wood. The easiest way to do this is to soak or boil the driftwood in water, in case it’s too big, use a large drum outside on an open fire.
If you plan on soaking your driftwood inside the fish tank, add some weight on the wood to keep the entire piece submerged. Howbeit, do not soak the wood inside your fish tank if the piece of wood is leaching. Instead, use a large container to soak the wood, which will help keep the tannins out of your aquarium.
How to Weight Down Driftwood in an Aquarium
Another way to get aquarium driftwood to sink is to weigh the wood in your tank. Enough extra weight can get the wood to sink, sometimes even sufficiently that you can remove the weight if you want to.
Most aquarists use heavy objects like lava rock to hold their driftwood down. However, if the piece of wood slips it will float, plus both the wood and rocks moving could damage your tank or hurt your fish.
For that reason, below are few tricks you can use to way your driftwood down.
**#1.**Screw a Piece of Slate on The Wood
You could drill a few holes in a small piece of slate then drive some stainless steel screws through the slate and driftwood.
The size of the slate will most likely be dictated by the buoyancy of the driftwood, plus the slate can get covered with the substrate.
Please note that only stainless steel screws are absolutely aquarium safe, other metals including iron will leach in the water column and could hurt your tank inhabitants, more so inverts likesnails.
Stainless steel screws are much safer than zinc plated or regular steel. I wouldn’t use galvanized either with the risk of oxidation. Brass is resistant to oxidation, but I would be hesitant to use it because it contains copper.
Slate is largely aquarium safe, but when in doubt, get a small piece and do the vinegar test. If it fizzes or foams on the rock, it’s probably not safe. Otherwise, it’s most probably safe.
**#2.**Glue Your Driftwood
This is not the option most freshwater aquarium owners would go for, but is easy and viable especially for smaller pieces of wood.
Super glue will help you attach a weight to your driftwood or anchor points inside the aquarium. If need be, you can even anchor the wood to the bottom of the tank, albeit making the wood hard to clean.
The glue should hold everything in place as long as it is a plank of good solid wood and the surfaces are clean and free from dust and debris.
Most glues are safe for use in aquariums, but to be sure, use cyanoacrylate gel (super glue gel) because it becomes completely inert when moist or wet. The active ingredient, cyanoacrylate, forms strong and stable bonds when in contact with water.
Alternatively, use epoxy designed for freshwater aquariums, which bonds and cures underwater.
One other thing to note is glue is only efficient when working with small pieces of wood, but for larger pieces, stainless steel screws are your surest bet.
**#3.**Drill Holes on The Wood and Tie It to Fishing Weight
Another, somewhat brilliant solution to keeping driftwood from floating is to drill a couple of small, inconspicuous holes and tie it to weight using fishlines.
Instead of tieing the wood on rocks, consider fishing weights since they are more decorative and sometimes easier to hide than rocks.
There is a lot of chatter on the safety of using fishing weights, but in my opinion, they are insoluble having been used for decades with fish in aquaria.
Moreover, if you are wary of the effect of metal, case in point lead, consider fishing sinkers made from other metals such as stainless steel.
Plexiglass pieces are also a common solution and alternative to metallic fishing sinker.