The Ultimate Guide To A Pond Bottom Drain

Bottom drains are more commonly found in swimming pools however many pond keepers are realising the amazing benefits that bottom drains can bring to their ponds. But what is a pond bottom drain? Well this article aims to answer just that and much more. 

What Is A Pond Bottom Drain?

A pond bottom drain collects all the dirt at the bottom of the pond and moves it through the drain and filter which removes dirt and debris out of the pond.

The drain is usually installed at the deepest point of your pond. This bottom drain is then connected to the pond filter via pipes. Once the water has been drained and filtered it should then return back into your pond as clear water.

When installing your pond bottom drain you will need a plumbing pipe running underneath the pond liner. To do this you will need to dig out a pathway for the pipe to lay in. From here you then cut the liner and push the drain into the pond. Installation is actually fairly simple.

Do You Need A Pond Bottom Drain?

In short, pond bottom drains are not essential for your pond. However, a pond drain can make a difference to the colour of your pond and help to keep the water clear.

Before building your pond, you should always check to see if your pond needs a pond bottom drain as once your pond is built it is almost impossible to install a bottom drain. If you are wanting koi in your pond, a bottom drain is essential for this to be successful.

Bottom drains are important if you have fish but specifically koi as it helps to remove the fish waste from your pond through the filter. Bottom drains help the filter to properly do its job.

Depending on the size of your pond, you may need several bottom drains for it to be effective.

In nature, many people rely on rocks to act as a bottom drain as this allows beneficial bacteria to grow but in these types of ponds you usually have a constant supply of fresh water, and you tend to have a fish population of about one fish per 30,000 gallons of water.

However, in a garden fishpond where you tend to have koi, you cannot rely on having fresh water constantly going into your pond so having a filter and bottom drain is always recommended.

In a garden pond you usually have a fish population of one fish per 150 gallons of water. So, unless you only have one koi in your pond and regularly change the water, you cannot duplicate what would otherwise happen naturally.

In wildlife ponds they do not need bottom drains, but this is not always the case with a garden pond. The conditions are very different. However, if you are unsure if you need a bottom drain, it is always best to check with professionals.

How Does A Pond Bottom Drain Work?

Pond bottom drains are designed to work with the force of gravity. All the debris and waste from the fish will use gravity to find its way into the bottom or middle of your pond. This is why your pond bottom drain needs to be at the deepest point of your pond.

The overall aim of a pond bottom drain is to transfer waste from fish and plant matter into a pre filter and then back into your pond as fresh water. This not only removes the waste from the pond but also helps to dissolve it.

Bottom drains usually have a fantastic flow rate of water which makes them very effective. Bottom drains work even better if you combine them with a quality aeration unit.

Pond bottom drains come in a range of different sizes, from 3-4 inches all the way to 8-10 inches in diameter.

Before installing a bottom drain into your pond, you need to ensure that you get the correct size, so it is best to speak to a contractor if your really unsure.

What Size Pond Bottom Drain Do You Need?

Ensuring you have the right size of pond bottom drain is highly important. If you have the correct size bottom drain, then this makes your pond flow a lot more effectively.

Most garden ponds will need a bottom drain of 3 or 4 inches. A 3-inch bottom drain has a maximum flow rate of around 1,800 gallons per hour and is suitable for ponds with an 8’ diameter pond bottom.

A 4-inch bottom drain works with a maximum flow of around 3,600 gallons of water per hour and works for ponds that are 10’ diameters at the pond bottom.

In short, the bigger your pond, the larger the bottom drain you will need.

What Is The Best Pond Bottom Drain?

The best pond bottom drains usually use gravity flow. Gravity flow is where the bottom drain is plumbed into a pre-filtration unit and drains water with a pond pump that sends the water to the filter.

Whatever the amount of water you drain from your pond you need to make sure that the same amount is going back in so that you maintain a stable pond level.

By using the gravity flow bottom drains the water is pulled from the pond through this pipe and into the pre-filter to ensure it is filled back up at the same rate hence these are generally the best to use.

With a gravity flow bottom drain, there are many installation options, so you need to pick the right one for you. Some bottom drain installations are a lot easier to maintain than others and of course the price varies. Most people do not like to plumb their bottom drains directly into the pump for a variety of reasons.

Conclusion

To conclude, pond bottom drains take fish waste and other debris out of your pond, through a filter before being pumped back into your pond as fresh water.

You need to install your bottom drain at the deepest point of your pond. Also, before installing a bottom drain you should check if you actually need one, a general rule of thumb is that wildlife ponds do not but garden ponds with fish, especially koi, do need pond bottom drains.

Lastly, if you do decide to install a bottom drain, you need to check the sizes. Most garden ponds will need a bottom drain of between 3 to 4 inches.