Benefits of Using Alder Cones in Your Shrimp Tank

Crystal Red shrimp by an Alder cone

Alder cones are a special type of miniature pine cone, which are safe and beneficial to add into your shrimp tank.


  • Lowers pH level
  • Great natural food source
  • Provides extra surface area for growing biofilm

Alder cones will release tannins into your water, making tannic acid and lowering your pH level.

This makes them very useful for tanks with Bee shrimp, as they thrive in more acidic environments.

However, the tannins can also cause your water to turn a dark tea colour, making your aquarium into what’s known as a blackwater tank.

It’s also believed that tannins have some antibacterial properties, which can help with keeping your shrimp healthy.

The rough wood texture provides a surprising amount of surface area for biofilm to build up on. All of the little gaps between the spines provide shelter for it to grow comfortably too.

This biofilm normally makes up the majority of a shrimp’s diet.

Alder cones vs Indian Almond leaves

The key difference between alder cones and Indian Almond leaves, is that alder cones are weaker in strength.

Indian Almond leaves will release a lot more tannins in comparison, so if you’re not a fan of the blackwater look, avoid the leaves.

Another obvious difference is that the leaves have a much larger surface for biofilm to live on. This means they can feed your shrimp more easily, and for longer, than alder cones can.

Otherwise, both options will give you similar benefits and drawbacks. If you’re happy making your water slightly tea coloured, try Indian Almond leaves.

How many alder cones should you use?

There isn’t a specific guideline for how many you should add to your tank.

You should start slowly and carefully monitor your water parameters and colour.

Starting with a rough guideline of 1 alder cone per 5 gallons is safe. Once you understand the effect they have in your specific tank setup, you may be able to use 1 alder cone per 2 gallons instead.

Effect on pH

Keep an eye on your pH level and the darkness of the water for a few weeks before you add more. Be careful not to lower the pH level too much and stress your shrimp.

Water with a higher buffering capacity, or carbonate hardness (KH), won’t have its pH level affected much. The tannic acid from the alder cones will be mostly buffered away. You might need to add quite a lot of cones before you see any noticeable change in the water’s pH.

Soft water with a low KH value, like in a Bee shrimp tank, will reduce its pH much more easily.

Blue Bolt shrimp on an Alder cone


As with most botanicals or leaf litter for shrimp tanks, you should boil the alder cones for a few minutes first.

Why do they need boiling?

Technically, you don’t have to boil them, you could just drop them straight in your aquarium, but it’s not recommended.

There are a few good reasons you should boil them first:

  • It reduces the risk of anything undesirable sneaking into the tank, e.g. parasites, and bacteria
  • It makes the cones sink quickly, as they absorb the water faster
  • It can help reduce the amount of tannins, preventing your tank water from getting too dark

Boil the alder cones for a few minutes, until they start to sink, and the water has gone a dark tea colour.

Drain the water to get your alder cones out, and leave them to cool down to room temperature.

The waste water can be poured down the drain, or used to water any houseplants that appreciate acidic water.

Alternatively, if you used dechlorinated water, you could pour this acidic tea water into your tank for more controlled blackwater. You’ll be able to make the water exactly as dark as you like then.

After the alder cones have cooled down to room temperature again, you can drop them into your tank for the shrimp to enjoy.

Completely dried alder cones can take up to a few days to sink, but boiling and soaking them beforehand should make them sink instantly in your tank.

How long do they last?

Alder cones will usually slowly release tannins for a couple of months. Eventually, they’ll run out and end up as a great place for collecting biofilm.

The woody texture and number of spines provided a lot of surface for bacteria and biofilm to grow.

You can leave the cones in your tank forever, as they’ll gradually break down and get eaten.

When should you remove them?

It’s totally fine to leave alder cones in your tank for months, as they gradually get eaten up and broken down.

You might find that the stalk gets left behind, after all the spines disappear. This can be removed if you don’t like the look of it, but it won’t cause any problems.