Cleaning Your Garden Pond

garden pond with fish swimming

When it comes to filtering the water elements of your garden, there are three basic methods of filtration: biological, mechanical, and chemical. The following advice demonstrates why you need to filter your garden ponds, pools, and other water features, and explains the various methods that might work best for you. Also included are tips to clean your water features when simple filtration devices are not enough.

Filters will keep your water clean and attractive-looking. A clean garden pond will allow you to keep greater numbers of fish healthy. Cloudy, stagnant water is seldom pleasant to behold, and a filtration system will rid your water of debris, fish waste, rotting plant detritus that becomes toxic, and so forth. For a healthy garden pond - fish or no fish - you have only to benefit from filtered water.

1. Biological Filter

A biological filter is often preferred by strict organic gardeners. Biological filters allow for aerobic bacteria to convert harmful ammonia into less toxic substances; this system is referred to as the nitrogen cycle. This is the closest to nature a gardener can get without leaving the pond to Mother Nature completely - which is not effective in manmade garden conditions. Basically, as fish and plant life is converted to ammonia, the bacteria in the biological filters first convert the harmful substance in nitrites and then finally into nitrates, which are beneficial to pond plants as a fertilizer. Keep in mind, these filters require oxygen-rich conditions, so the more plant life in your pond, the better these work.

2. Mechanical Filters

large pond with lily leaves

Mechanical filters are simple enough. With this type of filtration, pond water passes through a medium such as a sponge, gravel, or some kind of synthetic material and the wastes are trapped there. Generally, these wastes are then removed by back-flushing them into a drain. These are quite popular and there are many varieties available from online or local garden centers. Simply choose the one that is most adequate for the size of your water feature.

3. Chemical Filters

Chemical filtration is frequently chosen for new ponds that have not yet achieved a good water balance, but it can be used for mature ponds as well. A substance such as Zeolite in the form of chippings made from calcium and aluminum is added to the water. As water passes through the chips, the harmful ammonia becomes absorbed. This is generally how chemical filters work, but you will also find variations available.

Of course, part of maintaining a garden pond or other water element usually means testing the water from time to time. It makes sense to test to see if your pond is sporting an adequate balance and to see if your chosen filtration system is doing its job. Testing kits will allow the gardener to check levels of pH, ammonia, nitrite, nitrate, and protein. Anything out of whack can then be dealt with - the sooner the better. In such cases where your water testing kit indicates areas that need change, you can then apply a water treatment that will generally cure such problems as sludge, algae, or surface foam and restore your water to a proper balance. These too are available from online and traditional garden centers.

There are other devices available that will help gardeners perform routine pond cleaning. Pond vacuum cleaners are not miracle workers when it comes to cleaning up a real mess, but they are helpful at removing silt, sludge, and detritus. A simple pond net is necessary to get at floating debris, and pond scissors will allow the gardener to cut through dead or overgrown plants and pond weeds, which can be great hazards to the health of your garden pond.

Occasionally, your water pond may simply need a complete overhaul, although most experts say that with a good filtration system and proper maintenance, this should not be necessary. However, emptying your pond is not unheard of, and if it is needed, it is just part of the routine of caring for your water garden. The best time of year to empty and dredge your pond in order to clean the liner is between mid to late fall. In the case of a concrete pond, this is the time to check for hairline cracks that should be resealed with waterproof paint. Then it's time for a good scrub (be careful not to cause any tears if your liner is a flexible one) and start anew.

Of course, you will have to store your fish in such cases in large containers with the old water until the new pond water has a chance to settle. This is seldom convenient and never appreciated by your fish - it is traumatic for them - but they may have less chance for survival in a mucky pond. Your pond can be refilled by plain tap water using the hose, and this is the ideal time to get your filtration system kicked in so emptying will not be necessary down the road.