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What Should I Put in the Bottom of My Pond?

What Should I Put in the Bottom of My Pond?

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Building a pond on your property is one of the best things that you can do to improve the exterior aesthetic appeal of your property. A pond is a fantastic idea that will significantly improve the way your place looks.

If you have a spacious garden or a backyard, adding a pond is a fun DIY project that will not only improve the value of your property, but also give the place a cozier feeling.

However, while it is a great idea to build a pond, you should know that the process is not as simple as most people usually think. If you are under the impression that you can just dig up a hole and fill it with water, you might want to think again.

Digging the hole is just one step for building a pond. Once you have dug the hole, you will have to smooth it out and then lay pond liner on it. The liner is important because it prevents the water from escaping through.

Once you are done, you also need to think about putting something at the bottom of the pond. Some people usually just add the liner and let it be, but there are other options available to you as well, including gravel, rocks, and sand.

In the following few paragraphs, we will discuss the pros and cons of each material and then determine the best choice for lining the bottom of the pond. Let’s get started.

The Material Matters


Many people often argue that sand and gravel are a better choice for the bottom of the pond because it is natural-looking. After all, if you see natural ponds out in the wild, you know that there isn’t a liner at the bottom.

The first thing you need to know is that adding a pond liner is of critical importance. If you want to give the pond a clean and a stylish appearance, you should definitely consider opting for gravel or sand.

However, it’s imperative that you first lay down the liner before adding the sand or gravel. The pond liner is an impermeable membrane that is installed at the bottom of the surface.

They need to be protected from sharp objects otherwise they could tear. If the lining gets punctured due to any sharp object in the water, it could cause water to leak out from underneath into the soil.

If you have built a garden around the pond, it won’t take long before the soil becomes waterlogged due to water leaking from the pond, and many of your plants will die.

To protect the lining underneath, you will have to add sand or another material. This will also ensure that the pond liner remains trapped in the bottom.

However, there is always a confusion among most people about what they should put at the bottom of the pond. Some people argue that rocks and gravel are not a suitable choice.

They say that gravel and rocks can kill the fish and reduce the quality of the water.

Others say that the use of gravel and rocks is absolutely fine and it actually promotes good house bacteria that can break down the organic waste that usually falls at the bottom due to the fish in the pond.

But which one should you choose? The answer mainly depends on your own personal preferences.

Adding Just the Liner

Small Pond With Liner

Now, if you just add the liner and leave it at that, it offers a few pros and cons. The first major benefit that you get for choosing a liner bottom pond is that it is much easier to vacuum.

If you like to keep your pond clean, you might want to think about vacuuming the bottom at least once a week or maybe once a month. If you just have a liner at the bottom, this will not be a problem.

More importantly, you can just use a UV light to effectively kill natural bacteria that exist in the pond. Keep in mind that the UV light will kill both advantageous and destructive bacteria without discrimination.

As a result, there is a slight risk that the quality of your pond will suffer.

On the other hand, the downside to going for a liner bottom pond is that it results in a pond that is unnatural and doesn’t look very good. The reason why so many people build a pond on their property is because they want the pond to look and feel natural.

It should give an aesthetic and resemble nature. It’s why many people also introduce fish into their pond. If you have a liner, it simply won’t give such an aesthetic.

More importantly, you should know that the liner is generally frail and there is a risk that something sharp may cut it. If the liner tears, it could allow water to seep into the soil.

Heterotrophic bacteria also exist in natural ponds. These bacteria are able to consume the fish droppings and other aqua waste without much of a problem, and it helps maintain a robust ecosystem within.

However, without a liner, these bacteria would no longer exist so the pond will continue to get dirty over time. This is going to require extra effort on your part because you will have to regularly clean the pond.

The Gravel Bottom

Natural Looking Pond

Another choice is the gravel bottom pond. Right from the start, gravel bottom ponds have a more natural aesthetic. It will look exactly like the ponds found in nature.

Furthermore, it’s much easier to create a balance by adding a few plants, fish, and the right amount of filtration. Once you are able to strike this balance, the pond won’t need to be vacuumed on a consistent basis.

As you can imagine, it significantly reduces the amount of effort that you will have to make to keep the pond clean. The pond will have its own ecosystem.

The large area available at the bottom will also promote the growth of natural, beneficial bacteria.

But many people expect too much from such ponds. They often take things too far, completely ignoring their ponds. Without any maintenance whatsoever, the water will become more and more toxic, until the fish in your pond will begin to die.

Another important thing that you should know about these ponds is that they are slightly more expensive to build. The cost of the gravel and rocks is considerably high, and depending on the size of the pond, you will need to make a sizeable investment.

Gravel is generally suitable for a smaller pond. If you are going for a larger pond, gravel is not a suitable choice, even if you want the pond to contribute to the aesthetic of the space.

Large ponds generally have mud at the bottom, and that mud usually has a depth of several inches. By adding gravel on top, you are effectively limiting the microbial growth. The gravel also begins to mix in the substrate, which effectively reverses the benefits.

If you have a smaller pond, it’s much easier to manage. You just have to add the pond liner at the bottom and then layer it up with gravel on top.

The Best Method

Pouring Sand

If you have decided to build a pond and are getting started, the best thing to do after digging the hole is to lay down a couple of inches of sand. If you want, you can also spread a concrete layer at the bottom.

This is going to ensure that the surface remains smooth at the bottom and limit the chances of a tear. Small, sharp rocks are often the cause of tears in the pond liner, and this can cause a lot of trouble when it comes to repairs.

Once you have covered the bottom, you can lay down the liner and pin it from all sides. Now that the pond liner is set, the next step is to lay down the gravel.

A mixture of rocks and gravel is a wise idea, but don’t go too overboard as it’s going to affect the quality of bacteria in the pond.

Once you have laid down the gravel layer, you can then pour the water into the pond and decorate it. Make sure you add a filter and plant some algae as it will help in maintaining the ecosystem.

Remember, while this creates a sound foundation and ensures that your pond is able to thrive on its own, you will have to make sure that you clean it from time to time. For instance, after every few months, you should drain out the water and refill the pond.

Cleaning the bottom is also a wise idea. If you don’t get the time to clean out the pond all by yourself, you should consider calling a local company to clean it for you.

These are just a few things that you should know about selecting a suitable bottom for your pond.


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Saturday 12th of November 2022

My pond is concerted with the pipes on the bottom. What kind of screen, or how can we make a screen for the bottom???

DIANA Cooper

Friday 30th of April 2021

Hi Ben,

Thank you, this was very helpful. Just one thing about emptying the pond for a clean. I was always told never to take more than half the water out for a clean or you shock the fish and spoil the balance.

Best wishes from the UK. Diana.