Axolotls are fully aquatic neonatal salamanders that, much like fish, need a fully cycled aquarium to thrive in captivity. An important part of a fully cycled aquarium is your filter!
I recently had to deal with an illness in my axolotl tank (all my axolotls are okay!) that led to me completely taking down my established tanks so that I could disinfect them. That means that, unfortunately, my three axolotls are currently tubbed while I work on establishing a cycle in their newly disinfected aquariums. Having to start from scratch with my aquariums made me wonder, should I take this opportunity to switch what type of filter I’m using? In the end, I stuck with what I’m used to, but it did spark the idea for this post!
What’s the Best Type of Filter for Axolotls?
Axolotls can be quite messy, and they are a lot larger than your typical aquarium fish. They put a lot of strain on a tank’s cycle. They also prefer calm water, without a ton of movement. A lot of filters can generate a strong flow that can stress your axolotl. Finding ‘the perfect’ filter for your axolotl is a balancing act between finding one that will keep your aquarium clean by supporting the growth of beneficial bacteria, but also one that doesn’t cause a ton of water movement inside your axolotl’s tank.
Different keepers will also have their own personal preferences as far as what types of filters they prefer. Sometimes it just comes down to what you have experience with, or what type of filter you prefer having to regularly clean.
Sponge Filters
Sponge filters are, perhaps, the simplest (and the cheapest) filter option out there. They are essentially just, as their name suggests, sponges that you attach a pump and airline tubing to. The combination of a porous sponge plus a steady supply of air creates an excellent environment for the beneficial bacteria that work to keep your axolotl’s home toxin free.
- Pros of sponge filters: Sponge filters are easy to clean (they just need to be squeezed/rinsed out in a bucket of aquarium water), cheap, and, depending on the air pump you use with them, can be very low flow.
- Cons of sponge filters: Sponge filters don’t always remove as much debris from the water as other types of filters. They should be cleaned out more often than other types of filters, sometimes as often as weekly. Sponge filters require an air pump to work, which are usually sold separately.
Sponge filters are what I’m currently using in my axolotl tanks. I’ve been quite happy with these ‘Aquaneat aquarium bio sponge filters‘, coupled with this adjustable, ultra-quiet fish tank air pump.
Canister Filters
Canister filters are external filters that sit outside of your aquarium rather than inside it, as other types of filters do. Dirty water runs from inside your aquarium into the canister through connecting tubes, where the water travels through various types of filter media. Media inside the filter removes debris, and beneficial bacteria living inside the filter work to remove toxins. Clean water is then pumped from the canister filter back into your aquarium.
- Pros of canister filters: Canister filters provide more space for bio-media than other types of filters, and because they sit outside of the aquarium they don’t take space away from your axolotl.
- Cons of canister filters: Canister filters are typically more expensive than other types of filters, and they can be more complicated to set up and maintain.
Although I’m not using them currently, canister filters would probably be what I’d use if I decided to switch from my current sponge filters. They can be harder to set up and clean, but they, in a way, add more space to your aquarium because they increase your total water volume without taking up space inside your aquarium.
Hang on Back Filters
Hang on back, also called HOB, aquarium filters hang off the side (umm, or back) of your aquarium. They are somewhat like a ‘canister filter lite’, as hanging them on the side of your aquarium allows you to free up additional floor space for your axolotl. However, they are typically easier to set up than a canister filter as they don’t require a bunch of external tubing.
- Pros of HOB filters: HOB filters can be seen as a middle ground between sponge, or in-tank, filters and canister filters. They are easier to set up and clean compared to canister filters, and are also often more reasonably priced. They don’t take up floor space in your aquarium, which means more space for your axolotl!
- Cons of HOB filters: HOB filters can be harder to set up than simple sponge or in-tank filters. Because of their design, they can make it hard to find a cover that fits your aquarium properly, which is important for axolotls and other aquatics that can potentially escape from their tank.
In-Tank Aquarium Filters
In-tank filters are probably what most people think of when they think of aquarium filters. These are often plastic containers with built in pumps that are designed to hold filter media. Sponge filters are technically in-tank filters, but in this section I’m referring to filter types that, rather than just being one large sponge, contain compartments that allow you to incorporate changeable filter media.
- Pros of in-tank filters: In-tank filters are sponge filters on steroids. They allow you to add your own filter media, and change it without having to replace the entire filter. Unlike simple sponge filters, in-tank filters usually have built in pumps, so you don’t have to buy them separately.
- Cons of in-tank filters: Like sponge filters, most in-tank filters take up floor space inside your aquarium. When purchasing an in-tank filter, look for one that has low or adjustable flow for axolotls, who do not like the heavy flow that is the default with some of these filters.
Level Up!
No matter what type of filter you decide on, I’ve found it prudent, with axolotls, to buy a larger filter than what your aquarium size calls for. For example, if you have a 20-gallon aquarium, you can purchase a filter designed for a larger (60-gallon, for example) aquarium. Axolotls can get quite large, and they create a lot of waste, so a larger filter is better equipped to deal with their larger bio-load.
This will be especially important if you keep multiple axolotls in the same aquarium! Keeping 2 axolotls in a 50-gallon tank, for example, may provide your axolotls with enough space, but a filter designed for a 50-gallon aquarium may not be enough to handle the everyday waste of two axolotls.
Low With the Flow
Just make sure that, whatever filter you decide on, you can create a low-flow setting. Axolotls don’t like a lot of water movement in their aquariums, and a filter with a strong output can stress them out. Stress, in axolotls, can lead to a weakened immune system and sometimes to illness. So keep those salamanders stress free!
Some filters and air pumps come with settings so you can adjust their output. Some might have output tubes that can be moved or adjusted. Aiming them to disperse water against the corner or side of your aquarium can sometimes cut down on the amount of water flow they cause. Filters with spray bars are commonly recommended for axolotls because the bars disperse water more gently and evenly.
If you already have a filter, or accidentally purchase one that causes too much water movement, sometimes strategically attaching filter sponge to the water output area can be used to dampen the flow.
What Filter is Your Favorite?
Selecting the right filter for your axolotl can also just come down to which type you prefer. Maybe you’re used to working with a certain kind, or you’re looking for the lowest maintenance option. Whatever you select, make sure you always fully cycle your aquarium before adding your axolotl. Even after your aquarium is fully cycled, it’s a good idea to periodically check your tank’s parameters to ensure that your cycle is still going strong. A lot of different factors can impact your aquarium’s health, and thus your axolotl’s health as well. SO many of the most common axolotl issues can be prevented by staying on top of your aquarium’s parameters. A healthy aquarium is a healthy axolotl, and a healthy aquarium often starts at the filter!
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