You can spend an absolute fortune on a filter. Go to any water garden centre and take a look at the filters that are available. Apart from the actual choice being mind-blowing, the price tag is astronomical. They range from little plastic tanks to huge custom built, virtual sewage plants. It may be true that if you are going to have a pond purely for showing your fish, especially Koi, and if the quantity of fish is way out of proportion for the size of pool, then you would probably have to go for an all singing filter costing hundreds and hundreds. I say "especially Koi" because they are dirty blighter's! They look lovely but they love mud. I will delve deeper into types of fish on another page.
A filter, put quite bluntly, is a mini sewage processing unit. When fish go about their ablutions, and when small animals and plant matter multiply and die, the remains produce significant amounts of nitrogen and ammonia. Now these chemicals are perfect food for algae and plankton. If these chemicals are not dealt with, your pond will take on the dreaded pea soup appearance, eventually killing every living thing in the pond. Fortunately, nature has given us bacteria which, when in significant numbers, will munch away at these chemicals before the algae can take hold. The ideal filter will provide everything these bacteria need to multiply. The water garden specialists will tell you you need open cell foam, filter brushes, UV lights to kill algae, Pre filters post filters, the list goes on. You are left with the idea that filtration is such a precise science, the only way you will achieve success is if you get a ready made one. The good news is , most of the recommendations are just hype so they can get your money, and boy are they expensive. The fact is, all these beneficial bacteria need is a steady supply of oxygen, a steady supply of nitrogen and ammonia, and somewhere to anchor themselves; somewhere they can live in sufficient numbers to deal with all the waste a pond produces. As I have already said, a filter is a sewage plant, and we have had those longer than open cell foam etc. It's not an exact science. If the filter is bigger than it needs to be, it will work quicker, if its a bit small, it will take longer; but both will work.
My Home made Filter
