Troubleshooting a Garden Pond

Having a wildlife pond in your garden can really enhance the space. It can help encourage predatory creatures that will provide natural pest control. It can increase biodiversity and natural resilience and, of course, provide interest and entertainment for human inhabitants. But as spring turns into summer, and the weather warms, common garden pond problems can rear their heads. Here are some common problems that many ponds will encounter and how to solve them:

The Pond Has Turned Green

Algae and blanketweed are probably the most common problem seen in garden ponds. These bright-green blooms occur when there is too high a level of nutrients in the water or simply because there has been a lot of sunshine. If the problem is due to nutrients, this could be due to fertiliser run-off from surrounding soil, or excessive debris, leaves and organic material decomposing in your pond. Unfortunately, though small amounts of algae are beneficial in a garden pond, a sudden algal bloom can be a big problem. It leads to oxygen depletion in the water of your pond.

In the long term, a healthy pond with the right balance of plants can avoid algal overgrowth. Clearing out ponds in autumn and early spring will keep debris down. In the short term, daphnia (water fleas) provide a solution as these will feed on algae and help keep it down. Barley straw might also provide a partial solution.

Aquatic Weeds Are Taking Over

Aquatic weeds, both native and non-native invasive species, can quickly take over a garden pond and cause a lot of damage to the ecosystem. Duckweed is one of the most common weeds. These small floating, cress-like plants can cover the surface of your pond very quickly and this is the time of year when many pond owners will see explosive growth. Duckweed can be introduced with bought aquatic plants or brought in on the feet of visiting water birds.

Unfortunately, for most small to medium sized garden ponds, the best and really the only solution is to net or rake the duckweed from the surface and remove it whenever it gets out of hand. Remember to leave the duckweed (or any other aquatic weeds) that you have removed on the side of the pond for a day or two to allow any pond life living on or in it to escape and return to the water.

The Water Level Has Dipped Considerably

It is normal for ponds to experience fluctuations in water level. You can often see the water level in smaller ponds dip quite noticeably at this time of year as the weather warms and precipitation levels fall. You do not need to worry about this too much with larger ponds but smaller ones may benefit from a top up. Try to use harvested rainwater to do this if possible. If you have to use tap water then leave it to sit for 24 hours before you tip it in. You should only do this as a last resort. In larger ponds, you do not always have to top up your pond when the level falls but if frogs live in your pond, remember to provide them with means to leave the pond, such as a branch, plant, or length of pipe.