So, you want to add a pond to your yard? Excellent choice, but you probably have a ton of questions. While I won’t be able to solve all your problems, the one question I can answer is, “How deep should my pond be?”
The best depth for a garden pond is two to three feet. The water stays cooler and keeps microorganisms from growing, and this depth also gives more space to keep fish and plants healthy. Check local laws will tell you how deep you can dig your pond, and it might be illegal to dig deeper than two feet.
Depending on where you live or what you are going to use your pond for will change what depth you should choose. Read on to know about different pond types and the best sizes for each.
Before we get into pond types, it’s best to know why the best general depth for ponds is two to three feet (about 0.6 to 0.91 meters). Unsurprisingly, this mostly has to do with weather, and since ponds are outdoor water features, climate and weather conditions affect them directly.
They have to be a minimum of eighteen inches (about forty-six centimeters) deep in order to keep from fully evaporating during the summer or freezing over the winter. It would suck to walk out to your garden and find either a hole or an ice block where your pond should be.
Hot climates can evaporate the liquid in your water feature, and they also heat up the pond, making the small amount of water that remains a prime location for bacteria cultures or algae to flourish.
Unless you want a little rancid culture of green and brown pond muck rapidly regenerating in your garden, it’s best to stick with having your pond at the very least, eighteen inches deep, but two feet is a better benchmark to shoot for. If your local laws allow for a two-feet deep pond, it would be best to make it that deep.
Cold climates might keep a bacteria culture from forming in your backyard, but this also means that when winter comes around, you might end up with a block of ice.
It’s impossible to keep ponds from freezing over the top, but deeper ponds will have much more water and much less of a chance of freezing solid. Unless your goal is to start making mini ice-skating rinks for raccoons, it will be best to stick with ponds that are at least two feet deep.
Aerators and Dissolved Oxygen Levels
Deep ponds are great in many ways. However, having a deep pond also means that you will have to be very aware of the Dissolved Oxygen levels in your pond at all times.
Dissolved Oxygen (DO) levels measure how much oxygen is dissolved in the water. Generally speaking, the deeper the pond, the harder it will be to keep consistent DO levels throughout the entire body of water.
Low DO levels can be deadly to fish or any living aquatic creatures inhabiting your pond. It might seem like the best solution for this is to have a shallower pond, but that’s not a perfect fix. Fish need deeper ponds anyway so they won’t be swimming in a concentrated pool of their own waste (ew…), so sticking a couple of koi in a puddle isn’t the best solution.
The best way to keep DO levels high is to have a fountain or an air pump in your pond. These are both aerators, which effectively keep the water on the surface of your pond moving and interacting with the air, therefore dissolving more air particles into the water.
Surface aerators are fine for ponds from two to six feet, but for ponds deeper than that might want to consider getting a bottom (subsurface) aeration system, which might cost you more money.
If you want to spend less money on aeration equipment, or if you aren’t planning on having a fountain/air pump in your pond at all, it might be best to stick to the shallower side of things.
Many people get ponds with the goal of having their own little aquarium in their backyard. Who wouldn’t want to have adorable little fishes greet them every time they go outside?
But taking care of fish is a whole different ballgame. It’s definitely a worthy goal, but there’s a lot that goes into taking care of pond fish, and you should definitely do as much research as possible before digging into your backyard.
That being said, a pond should still be at least two feet deep when it comes to keeping fish. If your pond is any shallower than that, the pond will freeze solid during the winter (killing all your little watery friends), not to mention, a shallow pond will fill up quickly with fish waste, contaminating all the wildlife and also killing the fish. When it comes to keeping the ‘lil fishes alive, go deep or go home.
When I say deep, I mean deep. Two feet is still really shallow for a fish pond, especially for some species. Koi fish are the first that come to mind, after all, they’re one of the most common fish species for people to plop into their gardens. And for good reason; koi fish are beautiful and radiate a sense of peace and tranquility. But these same fish need a minimum of three-foot depth in their ponds. Four koi fish need around one-thousand gallons of water in their ponds.
Different fish have different needs. If you click the link below, you can see that this website has provided a list of prime fish species that do well in garden ponds (especially during the winter):
The more fish you want in your pond, the deeper and wider it should be. Some fish species reproduce more frequently and with more offspring than others, so be mindful of that while searching for your perfect pond fish species.
Take everything I said about having a “minimum depth of two feet,” and chuck it out the window. Wildlife ponds are the exception to the rule, mainly because wildlife ponds have a much different purpose than the other types of ponds mentioned.
Wildlife ponds are wide and shallow. They’re meant to provide water for any and all wildlife in the area. If this made you think of a watering hole, then you’ve got the right idea. These ponds are meant to be the human equivalent of a water fountain for wild animals, and since that’s their only purpose, wildlife ponds aren’t meant to be deeper than twelve inches (about thirty centimeters).
It’s essential that these ponds are shallow so that small animals can easily get in, quench their thirst, and then just as easily climb back out again.
Wildlife ponds will be at mercy of the elements, and probably will freeze or evaporate during harsh seasons, but that’s alright. When this type of pond freezes over during winter, most of the animals that would’ve used it are busy hibernating. These ponds are so wide and shallow that even if they evaporate, they’ll just refill the next time it rains.
These don’t need to be full of water all the time since they’re not supplying an ecosystem. It’s just a pond of water. A nearby herd of deer can come by, take a few swigs, and then galavant off into the sunset.
Most people don’t have the land for such a wide pond, but if you happen to own a large chunk of land, it wouldn’t hurt to drop a few wildlife ponds over your estate to keep all the cute squirrels and birdies happy and hydrated. I mean, what do you have to lose?
Ponds for Plants
Some people want pretty fish, some people want watering holes, and some people want to start their very own aquatic garden. When it comes to pond plants, the rule still holds up: Ponds should still be from two to three feet deep.
Planning to have a pond just to increase the greenery in your backyard is a wonderful idea. Plants are a great addition to any pond, providing nutrients and oxygen for fish, and preventing algae from growing. They’re also beautiful and provide natural scenery.
But just like with a regular garden, you will need to do research to know what plants like what water depths, what temperatures, and more.
Different plants need different water depths in order to survive. If you have your heart set on a certain water lily, it would be best to look up what depths they work best with and then go from there.
There are five types of pond plants, classified into zones.
- Zone 1: Bog Plants (usually reside in mud around water)
- Zone 2: Marginal Plants (0-10 inches)
- Zone 3: Deep Marginal Plants (6-10 inches)
- Zone 4: Submerged Plants (12-24 inches)
- Zone 5: Floating Plants (they float on the surface, so depth doesn’t impact them as much)
Something you’ll notice from all these plant zones is that their preferred depth all falls under two feet deep. When making a pond garden, it will be more important to focus on how deep each ledge is, and making levels for each part of your pond in order to let plants of different lengths thrive in their preferred depth.