Sponge is an excellent starting point for filter media, especially for hobbyists looking for an affordable and reusable option. To maximize filtration, it’s essential to choose a sponge with a higher pore density than a typical kitchen sponge. Ideally, you want a sponge with 20-30 pores per inch (ppi). This ensures that microbes can settle in the pores to carry out biological filtration, while still allowing water to flow through without clogging too easily.

Using sponge filter media enhances biological filtration, though it does come with a trade-off in mechanical filtration. Over time, the sponge will inevitably clog as debris builds up, but cleaning it is straightforward. Simply rinse the sponge in old tank water to remove the gunk, and it can be reused for an extended period—often indefinitely. This makes sponge filters both cost-effective and sustainable, offering an efficient way to maintain a healthy aquarium environment.

Plastic pot scrubbers are one of the most budget-friendly filter media choices available. They're easy to find in large quantities, and their structure provides an excellent surface area-to-volume ratio, which is key for efficient biological filtration. Like sponge, plastic pot scrubbers are easy to clean and can be reused multiple times, making them a sustainable and cost-effective option for filling your filter.

It's important to note that you should only use plastic pot scrubbers, not steel wool, as steel can rust and release harmful substances into your tank. When properly maintained, plastic pot scrubbers can offer long-lasting filtration, supporting a healthy aquarium ecosystem without breaking the bank.

Filter floss, which resembles the fake cobwebs you often see around Halloween, is an excellent option for mechanical filtration. It effectively polishes the water by trapping fine particles and debris. However, it does have a downside—it clogs quickly and requires frequent cleaning, which can become a tedious task. While it isn't as beneficial biologically as other filter media, filter floss plays a vital role in keeping the water clear, especially in setups that need extra mechanical filtration.

Many filter cartridges are lined with a layer of filter floss, making them a great choice for polishing the water, provided they are cleaned regularly. Just be prepared for the extra effort involved in maintaining it.

Ceramic media is a popular choice among hobbyists due to its high surface area-to-volume ratio, making it an effective biological filter media. Available in various shapes and sizes, ceramics provide ample space for beneficial bacteria to thrive, helping to maintain a healthy tank environment. While not all surface area is fully utilized (as some areas may not get adequate water flow), ceramics still offer great benefits for biological filtration.

One downside to ceramics, especially in freshwater setups, is that they can accumulate debris and waste over time. However, they are resistant to gunk buildup, with bacteria thriving on their surfaces without much interference from particles. This makes ceramics a solid option for supporting a healthy microbiome in your tank.

Kaldnes media, often resembling wagon wheel pasta, is designed primarily for fluidized filtration in sumps but works effectively in various aquarium setups due to its impressive surface area. These media pieces allow for efficient water flow through their structure, promoting biological filtration and providing plenty of space for beneficial bacteria to thrive.

Though typically used in sumps, Kaldnes media is highly versatile and can be used in different filtration systems. They require minimal maintenance, as they rarely need cleaning due to the efficient flow through them. The standard K1 media is widely known, though there are various versions of Kaldnes media, each offering similar benefits.

Filter media comes in various shapes and sizes, with plastics being a popular choice due to their ability to be molded into intricate shapes without compromising water quality. Bio balls, a well-known plastic option, are favored by many hobbyists, though they can be costly given their niche market appeal.

Many plastic materials serve as excellent filter media, as their small and complex shapes provide ample surface area for beneficial bacteria to colonize while still allowing water to flow freely. These types of media are great at supporting biological filtration, making them a practical choice for maintaining a healthy aquarium environment.