Hedge plants

Sludge in the garden pond - Instructions and tips for sludge reduction


Well, where did the fish go? If the water is so cloudy that you can no longer see it, it is high time to desludge the garden pond. Here is a guide.

Garden pond always in the spring

What falls into the garden pond all year round and seeps to the bottom is very remarkable. Algae, dead plant parts, fish excretions and food residues that sink to the bottom also do the rest. No wonder that a thick, slimy layer of mud forms over the course of time, which on top of that further cloudes the pond water. Then at the latest you have to act and sludge the garden pond. If you don't do this, it can happen that at some point you will have a smelly mud hole instead of a beautiful biotope in the garden.

When is the best time to desludge?

The best time for desludging is in the spring, before you put your fish back in the garden pond. So you don't have to catch them again later and put them in water tanks to desludge your garden pond, because you have to drain all the pond water to do this. This will save you and your fish a stressful ordeal.

Pond vacuum cleaner with little pollution

If the water in your garden pond is only slightly contaminated, the use of a normal pond vacuum is sufficient. These 3 models are popular:

1 Kärcher multi-purpose vacuum cleaner WD 3 Premium 1,416 reviews89,99 € 62,99 €To the shop
2 Wiltec pond vacuums pool vacuums sludge vacuums… 7 reviews84,35 €To the shop
3 Pontec pond & pool vacuum cleaner PondoMatic 199 reviews119,95 € 101,99 €To the shop

If the silt is heavier, you should follow the instructions below.

Instructions for desludging a garden pond

➥ Step 1:

First of all, you have to remove all the water from the pond. This is particularly easy with powerful pumps. This also has the advantage that the aquatic plants are not exposed to the sun and the heat for too long.

➥ Step 2:

Once the pond water has been completely drained, you must then relocate and check all the water plants. For example, cut back aquatic plants that have become too large and also cut off unsightly shoots.

3 Step 3:

Now it is time for the actual work: desludging. You have two options. On the one hand, you can use a special sludge cleaner that can be borrowed from a specialist company, or you can work with a bucket and shovel. So first remove the sludge layer.


Be careful with this step! This is the only way to prevent the pond liner and the pond fleece behind it from being damaged.

Tip: Polygard.de offers pond liner directly from the manufacturer.

4 Step 4:

Now a high-pressure jet should be used, as it can be used to remove sludge and algae growth particularly effectively from the pond liner and stones.

Then pump off the resulting polluted water.

5 Step 5:

If the pond is completely empty, you should also check the pond liner for damage and repair it if necessary.

6 Step 6:

If the pond is clean, you can fill it up with fresh water and use your pond plants and fish.

Sludge reduction tips

There are some things you can do to prevent a thick layer of mud from forming on the bottom of your garden pond. Just follow the tips below and you will save yourself regular sludging in spring.

➤ Tip 1 - Put aquatic plants in the pond:

In order to give algae no chance at all, aquatic plants are essential in a garden. These remove the nutrients from the algae. On top of that, regularly cut back the aquatic plants, they bind even more nutrients through their growth, which means that the algae practically starve.

➤ Tip 2 - Spread the leaf net over the pond:

Especially in autumn it makes sense to stretch a net over your garden pond so that the autumn leaves do not fall into the water. This cannot rot in the pond and therefore cannot contribute to the formation of a layer of sludge.

➤ Tip 3 - fishing for algae:

It is also important that you fish out algae regularly so that they do not spread explosively in summer. Fishing reduces the nutrients in the water, which in turn prevents the algae from multiplying. These 2 seaweed nets are popular:

1 Oasis professional landing net No reviews at the moment33,89 €To the shop
2 Söll 18829 landing net, algae landing net extra-fine, triangular… 37 reviews29,99 €To the shop

➤ Tip 4 - use ecological pond sludge remover:

If you use an ecological pond sludge remover, the sludge layer does not become so thick at all. This product breaks down the pond sludge with the help of oxygen-producing bacteria, which keep algae formation at bay (reading tip: How algae develop in the garden pond). The pond water becomes wonderfully clear again just a few hours after using the ecological pond sludge remover.