At the heart of most fish ponds and aquaria is the filtration system. This might be a complex, large filter such as used with koi ponds, or a simple canister often seen with aquaria. Whatever the size or shape, filters work continuously to "purify" the water. An understanding of filtration systems is important for healthy fish keeping

Biological filtrationNitrification

Is a biological process during which nitrifying bacteria convert toxic ammonia nitrate.

Sources of pollution

Often there is a failure to understand just how rapidly and to what degree koi pollute the water they live in.

Organic Pollution

This form of water pollution indirectly affects koi health by encouraging high levels of opportunistic bacteria and parasites, as well as affecting overall water quality.

Removing solids from the system

If we could remove the solid wastes from the system before they had chance to dissolve and pollute the water we would have better water quality, less dissolved pollutants and fewer health problems.

Biological filtration & filter media

What's the difference between the sometimes bewildering and conflicting claims made for various filter media?

Flow rates & retention times

Although a detailed understanding of filtration mechanics is not essential, this page does explain why some filters work better than others. Retention times are more important in cases where the water is not allowed to re-enter into the filtration system a second and third time. With proper turnover, nitrogen is reduced in several passes and very few systems need worry about retention times unless they are not reuse systems. Still, there are a lot of over-stocked koi ponds with pretty poor filtration systems.

Goldfishworld.com would like you to take a look at the new filtration system coming to the forefront in the USA. Bead filtration uses beads for it's media, and they are a snap to clean. The bead filtration system made by Aquadyne (in particular) is like no other bead filter, and it's taking the US market by storm.