When should I clean out my pond?
Not too often
A well designed and planted pond should not require frequent total clean-outs if properly maintained. Indeed, cleaning too often can upset the natural balance of the pond and lead to more problems with blanketweed and green water.
The need for cleaning can be reduced by:
- Keeping out excess fallen leaves with a good quality cover net in the autumn
- Trimming back and composting excess plant growth
- Removing and composting invasive plants* © www.watergardensolutions.co.uk
- Removing dead and dying foliage in the autumn. Using a silt digesting treatment.
- Maintaining any pond filter and cleaning when appropriate
- Netting or raking out excessive blanketweed or duckweed growth
As an alternative to a full drain and clean:
- Part change the water (30-60%) topping up with rainwater and/or tap water with a suitable conditioner
- Carefully net debris off the pool base.
- Split/trim and replant basket-grown waterlilies and marginals in fresh soil every 3-5yrs
A complete pond drain and clean might be necessary every 5-10 years - generally the longer interval for bigger ponds. It’s certainly time in an average garden pond when the silt depth reaches or exceeds 10-15cm (4-6 inches). It helps to have temporary aerated storage bins/vats to keep fish and wildlife in whilst the clean takes place. Saving some of the old water, even if it is cloudy, will seed the new pond with valuable micro-organisms and help the refreshed pond to settle down faster. It is common for newly cleaned ponds to have more noticeable blooms of scummy green algae or blanketweed in the spring/early summer of the following two years or so. This is due to additional nutrients from the new water and planting soil used, but usually settles down as the plants and micro-organisms re-establish. Use of blanketweed controls may be of use.
What time of year?
The best time to clean out is probably late summer to early autumn. This still gives a month or so for plants and fish to recover before the winter arrives. Spring is another possibility, though this time is more disruptive to amphibians. Avoid cleaning out during the hottest summer months or in cold weather (below 8-10 deg C). However, if your pond has Great Crested Newts (legally protected) you should leave maintenance to the winter months when they are less likely to be in the pond (Government advice)
If you are in doubt about how to handle your pond Contact Us to find out how we can help.
*Some of the more aggressive invasive plants such as Stonecrop (Crassula) and Water Primrose (Ludwigia), do not compost well in domestic bins, and should be disposed of more cautiously.