How can we make fishkeeping greener?

I have kept tropical fish for almost four years and have always tried to run my tank in as natural a manner as possible, choosing live plants and natural decor over plastic alternatives. But it has occurred to me that fishkeeping uses an awful lot of plastic, in filtration systems in particular. Are there any natural or biodegradable alternatives to plastic filter media that would be safe to use? And are there any other ways I can make my fishkeeping more ethical, and more natural for my fish? ESTHER CLARK, VIA EMAIL

NEALE SAYS: When it comes to plastics, the ’three Rs’ are a good starting point: reduce, reuse, and recycle. Realistically, the easiest way to reduce the use of plastics for things like filters and aquarium hoods is to choose designs known to have a long working life. The availability of spares is important as well. If you take something like a canister filter, if the casing starts to leak because the rubber seal as perished, that’s a lousy reason to have to throw the whole filter out. So, if you can replace the parts, the amount of plastic you throw away will be dramatically reduced.

One bugbear of mine is the plastic sponges that some manufacturers suggest need replacing every six months or so — if you clean them periodically, they should last as long as the filter. Synthetic filter wool isn’t as durable, of course, and you might well decide not to bother using it at all. Its job is to ‘polish’ the water by trapping silt. Filter wool pads tend to be made of fibres rather like nylon and don’t degrade appreciably when used even across several years, but they do become more matted with dirt and harder to clean. The more frequently they’re cleaned, the longer they last. Some aquarists use cotton pads instead, and these are of course biodegradable.

You can side-step the use of some plastic media by relying on glass or ceramic alternatives. These tend to be more expensive, but being chemically inert, have minimal impact on the environment. The better brands, such as Sera Siporax, are exceptionally useful and versatile filter media. Cleaned regularly, ceramic and sintered glass media should have lifespans measured in decades.