How Small Can a Garden Pond Be

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One of the most critical factors you can consider is pond size when working with a garden pond. Pond size will determine what kinds of fish you can have in your pond, what climate it will be best in, and how often you’ll need to maintain it. But how small is the smallest possible garden pond?

If you really want to start up a garden pond but don’t have as much room as some others, you could get away with a pond 8 ft. wide by 8 ft. long and at least 4 ft. deep. Anywhere below that depth, and your pond won’t be able to maintain a viable ecosystem.

But why these measurements? Are there any exceptions? In this article, we’ll talk about how where you live and what you want your pond to be like may affect your garden pond. Along the way, we’ll define some basic pond terms and work out what it takes to build a good garden pond.

Minimum Size of a Garden Pond

When we talk about size in reference to garden ponds, we’re most likely talking about length and width. The length and width of a garden pond will determine how big the surface of your pond is and how much square footage it will take up.

Most people’s thinking about pond size stops there- if I’ve got the square feet free, why not build a garden pond? But these people aren’t thinking below the surface level.

When we’re considering pond size, we’re really talking about volume- volume is just how much water a pond can hold in 3d space. So when we talk about surface area, we talk about the flat plane of water across the pond’s surface. When we talk about volume, we talk about all the space below that surface.

According to Sacramento Koi, the least recommended volume for your average garden pond is about 1500 gallons, which translates to a pond 7 feet wide by 8 feet long and 4 feet deep. We recommend adding one more foot to that width just to square everything off and make the building process easier.

Want to find out more on how deep should a garden pond be, check this out!

But that doesn’t mean these are the only possible measurements for a 1500 gallon garden pond. You could decrease your depth, for example, but you’d have to make your pond wider or longer to make up for the loss in volume.

If you’ve got the space, though, most sources recommend making a wider pond. For one, more expansive ponds are more like natural ecosystems and serve as an excellent place for an exceedingly wide variety of lifeforms to grow and flourish- and isn’t this the point of making a big and effective garden?

And for another thing, bigger ponds are just a lot easier to maintain. Larger ponds are harder to warm up, meaning they serve as an excellent place for algae to bloom. We’ll talk about why this is bad in the next section, as well as how pond maintenance on smaller ponds can get taxing.

Why Are Smaller Ponds So Hard to Clean?

When most gardeners build a garden pond, they choose to go with a much broader design instead. Wide ponds are beautiful, biodiverse, and they can be a real reward to upkeep, considering that they require little maintenance.

If you’re working with a small backyard, you may have to level-down your pond in an attempt to work with the limited space. That doesn’t mean you can’t have a beautiful and diverse pond. It just means it will be much harder to maintain. But why are smaller ponds harder to maintain?

The problem with small pond maintenance stems directly from the problem of algal bloom, which becomes a problem in shallower ponds that heat up more quickly than larger ones. Algal bloom can completely ruin ecosystems and must be cleaned out before it becomes too big of a problem. 

Basically, algal bloom is an over-abundance of algae in your garden pond’s ecosystem. When you get too much algae in your pond, your fish, plants, and other creatures can’t get enough oxygen from the water to survive. Not to mention, it just becomes too cluttered for anything to live.

Algal bloom usually occurs in nature when a source of fertilizer contaminates a nearby water source. In this case, the algae uses the fertilizer to grow beyond a manageable volume, thus killing other lifeforms and monopolizing the water source’s oxygen supply.

But algal bloom doesn’t always depend on an over-abundance of fertilizer. That just creates the nutrient-rich conditions that algae need to survive. There are other ways to create an algae-prone environment that’s likely to pick up a spot of algal bloom.

Heat. Or, too much of it. You see, algae love warm, wet environments with lots of nitrogen, iron, and other nutrients. When they find a warm strip of water, they usually grow as far as possible without running out of nutrients.

In natural ponds, algae are limited in their expansion by the lack of nutrients out in the center of the pond. This limiter gets tossed out the window when a pond is contaminated with fertilizer.

You might have noticed that thick patches of algae usually grow on the sides of ponds, nearest the banks. This is because a shallower stretch of water is easier to heat up- like how if you boil a gallon of water, it will take longer to heat up, and it will maintain its heat better than a liter.

Think of your smaller pond like the liter of water or the banks of a natural pond. Because your pond is so small, it’s easier for the sun to heat it up, providing the perfect place for algae to run rampant.

Find out more on should a garden pond be in the sun or shade to give some detailed answers on this.

Combine this with all the fertilizer and nitrogen in your garden, and what you’ve got is a recipe for disaster. You might end up having to clean out the algae in your pond every other day, disrupting the ecosystem and seriously tiring yourself out.

For Smaller Ponds, Deeper is Better

While a smaller pond will always be harder to maintain, there are a few things you can do to prevent algal bloom from happening and decrease the maintenance burden on yourself. These methods are simple and intuitive and won’t take much time or effort.

The first and foremost method for keeping your pond clean is to make it deeper. Depth also plays a role in what kinds of fish you can have in your pond and just how much the sun will be able to heat it up.

With a deeper pond, fertilizer in the water will sink to the bottom and become sediment. Down there, algae will not be able to reach these nutrients, and it won’t be able to bloom out of control. You don’t want no algae in your pond- some fish and creatures eat algae. You just don’t want it to cover the whole pool.

For this reason, a depth of at least two feet is recommended. Keep in mind, you want to stick to the 1500 gallon mark- we’re just saying that if you don’t want to build a Mariana trench-deep pond, you can get away with something a little shallower. Just don’t go below 2 feet in depth.

Pond depth also plays a role in what kinds of fish you want to buy. If you’re only planning on getting a few little goldfish ‘n guppies, then don’t be afraid of a shallower pond. These fish are small and require comparatively little space to live comfortably.

Koi, however, are going to need a little bit more space. For these fish, we would really recommend sticking in the 3-to-4-foot-deep range, just for good measure. They’re going to want lots of good space to roam- just like you want lots of house-space.

The minimum depth of your pond will also change based on climate. If you live in a colder climate, you’ll most likely have to build a much deeper pond, so your fish will have somewhere to retreat to when the temperature starts to drop and the water begins to freeze.

So, overall, you’ll be safer if you just shoot for a deeper pond. We know that digging a deep pond can be a cumbersome task, but if you don’t want to perform constant maintenance- and if you want to keep your fish- you’re going to have to suffer through it.

Plus, a deeper pond can be must smaller. We wouldn’t recommend going anywhere below 7 ft. in length, but if you’ve got a 4-foot deep pond liner, you can really put it in any kind of backyard. So don’t create worries you don’t need in your life- dig a deep garden pond and relax to the sound of a living pond ecosystem.

All in All

All in all, there are all sorts of small ponds you can get away with- just keep in mind that depth is better because it’s easier to maintain. Don’t go anywhere below a 7 ft. by 8 ft. surface area with a 3 or 4 ft. depth, and make sure to enjoy your pond to the fullest.

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