Every pond made by man should have a liner, and some also suggest having a layer of sand and gravel. While a liner is a no-brainer (the pond will leak into your lawn and garden), a substrate like sand or gravel can be controversial.
There are advantages and disadvantages to using sand or gravel, and there are advantages and disadvantages to using a liner only.
Learn more below!
Just a Pond Liner
Many people simply utilize a liner in their pond, ignoring sand and gravel.
This primarily is because it really can make things simpler.
Firstly, you will not have to worry about getting and distributing an appropriate substrate.
Secondly, cleaning a pond that just has a liner will be much simpler because you can just use a pond vacuum!
On top of that, pond liners do not permit algae to grow like sand and gravel do.
So when cleaning day comes, there should be very little debris!
Pro’s
- Cleaning is simple and easy
- Inhibits the growth of algae and other kinds of pond gunk
- Provides a blank backdrop so any fish or pond critters can be seen clearly
- Creates a modern look
- Long Guarantee with liners
Con’s
- Doesn’t look quite as natural
- The pond wildlife might be more comfortable in sand or gravel
- Many (but not all) pond plants require sand or gravel
- Expensive
- Heavy to install
Sand
Sand is used largely at the bottom of ponds.
- Primarily as a decorative element.
- And also to allow some aquatic plants to establish.
What kind of sand is best for your pond bottom depends in part on what wildlife you have. For example, if your pond has catfish, they are a bottom feeder, and will scrape their stomachs on rough sand.
In this case you would want some better quality, smoother, aquarium sand. If all you have is koi, it won’t really matter as much.
Sand does supplement plants, but does so with bacteria as well!
So if your sand (and pond) are not filtered or cleaned properly, your interesting wildlife pond residents will get sick!
Sand will also probably make cleaning the pond bottom somewhat more difficult.
You won’t be able to just use elbow grease and a vacuum cleaner but probably to replace the sand.
You will also probably be cleaning a lot of algae and sand!
Pro’s
- Needed in order for certain plants to grow successfully
- Bottom-feeders (like catfish or corydoras) tend to prefer it
- Can help filter the water
- Creates a more natural look
Con’s
- Can make cleaning more difficult overall
- May comparatively encourage bacteria that can make pond critters sick
Gravel
In comparison to a standard liner, gravel will provide you with a significantly more natural appearance, much like sand does.
In addition, it tends to hold together a little less than sand does, allowing for more aeration and more bacteria interaction with the substrate, cycling decomposition of detritus and making for a cleaner pond environment!
Some people believe gravel is a breeding ground for harmful bacteria; others believe the opposite—that gravel helps filter the pond.
There are arguments for both of these perspectives, so in the end, it may just come down to personal preference. Also, unlike with sand, using a pond vacuum is possible if the gravel is large enough.
Some gravels may be too sharp for bottom-feeders, so that is something to also consider if you have bottom-feeders!
Pro’s
- Creates a very natural look
- Some say it helps filter the pond water
- Some underwater plants require a substrate (such as gravel) to grow
Con’s
- Some gravel is too rough for bottom-feeding/bottom-dwelling fish
- Some say it can encourage harmful bacteria and gunk
- Koi have been known to get sharp gravel stuck in their mouths
Clean Your Pond Regularly or Put the Health of Your Wildlife at Risk
One of the common issues with wildlife ponds is that they aren’t cleaned often enough.
Sometimes, they are never cleaned! This is not only unsanitary, but it could jeopardize the health of your pond’s wildlife!
In all actuality, it is more important to have a clean pond than it is to worry about what’s in the substrate.
When a pond’s substrate goes untouched, harmful bacteria and sulfur will form, which is essentially deadly gunk.
Just remember: A pond should be clean at least once a month, to prevent things like this!
Are Rocks or Pebbles Good for a Wildlife Pond?
If you’re in search of an alternative to a liner at the bottom of your pond, trying some smooth rocks or pebbles could work as well.
Usually, these are large enough that you can use a pond vacuum around them and sucking them up won’t be an issue!
Pond Plants for Oxygen and Decor
Plants can be the perfect decorative item in a pond because, besides anything else, they will give your pond that natural look you’re searching for!
In addition to that, they will provide a natural filtration system, breaking down detritus and converting CO2 back to O2 that your pond wildlife will be thrilled to breathe!
- Water Starwort
- Water Violet
- Cardinal Flower
- Water Lettuce
- Mosaic Plant
- Willow Moss
- Microsword
- Water Lilies
- Yellow Flag Iris
- Chameleon Plant
- Hornwort
- Marsh Marigolds
- Horse’s Tail
Final Words
Therefore, if you were asking yourself, ‘what do I put in the bottom of my wildlife pond,’ now you have your answer: the liner, or sand, rocks or gravel.
It really depends on both your own preference, and what you are hoping to achieve.
On a side note, it is also just as important to be cleaning your pond about once a month, to keep all the bad bacteria etc… in check!