To choose the best water garden filters, consider the size of your water garden, whether you want biological or mechanical filters, and where you want to put them. In order to keep your water garden or pond functioning properly, make sure you have adequate filtration for the amount of water you are working with. You will choose between using a biological or mechanical system or a combination of both. Where you put your water garden filters can affect the overall look of your water garden, so it is an important consideration as well.
The first thing to think about when shopping for water garden filters is how much water you need to filter. If you don't get a big enough filter, you will eventually have to deal with algae problems and a water environment that might be harmful to any fish you have. Look carefully at how much volume the filters can handle. You can find volume calculators on some merchant websites to help you determine what size is best. As a general rule, it is better to have a filter that is too big than one that is too small, so if you are ever in doubt choose the bigger one.
Mechanical and biological water garden filters can both be effective. A mechanical filter uses a pump to force water through a man-made filtration material that catches debris and algae. A biological filter also involves the use of a pump, but the water passes over a natural filter such as rocks or a UV light that naturally controls the amount of algae and debris that get past it. A biological filter can also refer to adding bacteria or algae to the water garden to convert ammonia into useful nutrients for plants and fish.
Choosing between mechanical and biological water garden filters often comes down to what type of water garden you have. If you have a waterfall then you already have a biological filter built in that you simply have to maintain. A mechanical filter with a skimmer can be very effective, but it has to be installed on the outside of the pond and can take up a lot of space, so it is usually best in larger water gardens. For many people, a combination of both types of filters works the best.
A submersible water garden filter is often the cheapest choice and is good for smaller ponds, but it can be visible in the water and may be more difficult to clean. An external filter where the pump and plumbing can be camouflaged by parts of the water garden itself will cost more but might be more convenient and detract less from the overall look of the water garden. Think about where you have space to install a filter within your water garden and how you want it to look when you are done.