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Having a pong in your garden is a spectacular experience. Nothing compares to the sounds of crickets chirping by the water and little fish eating bugs off the pound’s surface. But how deep does a pond have to be to accommodate these fish? How far into the soil should you dig for your garden pond?
A garden pond should be at least 2 feet deep to avoid algal bloom. When light strikes as shallow pong, it has an easier time warming it up. Warm pond water is the perfect place for algae, fly larvae, and all sorts of other nasty things. Therefore, you’ll want to make your pond deep.
So, why does shallower pond water warm up faster? What kinds of advantages does a deep pond provide? And how do pond water layers work? This article will answer all these questions and more, hopefully touching on both the question you came here for today and a little something extra.
Why Do Shallow Ponds Warm Up So Fast?
Think about boiling water on the stove. If you’ve got two pots of water, one with a tiny splash of water in the bottom and one with a whole gallon of it, which one do you think will boil faster? If you said the bigger pot, you’d be correct.
This is because, as volume increases, the amount of matter in the pot also increases. To kick up the energy in that matter, you’ll need to put more energy into the pot- meaning a longer time to boil.
It’s the same effect with a pond. If you’ve got a 10 ft. X 1 ft. pond- more of a large puddle than a pond- you’ll notice it heating up rather quickly. Think of how when you dive into a pool, there’s a warm upper layer and a cold lower layer where your feet float.
The transfer of energy from sunlight to water in a pond also has to do with the pond layers.
Not many people know this, but freshwater has layers just like the soil does. Just as you’ll eventually hit bedrock when you dig, if you swim down, you’ll eventually reach the profundal zone.
The profundal zone of a pond is the area beneath the limnetic or light-filled zone where beams of sunlight cannot reach. Because sunbeams can’t reach this layer, they also can’t heat this layer. Thus, it stays cool and free from algae and other potentially harmful pond-dwellers.
With a very shallow pond, you won’t have either of the two advantages listed above, and the water will heat up just like if you had left it on the oven range. Because of this, you’re going to want to make absolutely sure that your pond is deep enough.
And besides, no fish likes to spend its whole life in a puddle. If you’re getting fish for your pond, giving them some depth to swim around in will increase their quality of life. Plus, you won’t have to go cleaning out algae quite as often.
Why is Algae a Problem
The whole reason algae poses such a threat to your pond ecosystem lies in a phenomenon called ‘algal bloom.’
What is algal bloom?-
In environmental science terms- algal bloom is when too much fertilizer builds up in a pool of freshwater, and algae have an overly-fertile place to grow.
Eventually, algae will take up a full pond, preventing other life like fish and frogs from living there, and creating a profoundly unhealthy ecosystem.
But too much fertilizer isn’t the only case that can cause algal bloom. Any pond that provides an over-ripe place for algae to bloom is bound to pick up algal bloom- and that means your little one-foot-deep puddle-pond.
So, when you’re building your pond, you want to make sure you keep the water nice and deep- that will mean not only digging your pond deep but providing an adequate lining so that water doesn’t seep into the soil below.
How to Keep a Pond Deep
One big mistake some gardeners make when they start building their ponds is to neglect a lining.
A pond-lining is a layer of some non-porous substance that will serve as the bottom of your pond. Often, these linings are made from PVC, concrete, or clay.
Notice how when the rain comes down, it doesn’t all just roll downhill to streams and rivers. Some of it stays stuck in puddles on your lawn. Evaporation isn’t the only thing getting rid of that water, though. It’s also seeping into the soil below.
Some areas will have naturally good soil for a pond- this is why ponds form naturally in the first place. Some other areas will have very porous soil- great for growing and gardening but not so good for retaining water.
If you live in an area with clay soil, you’ll likely have a much easier time creating a pond naturally. If not- if you’re living in an area of loamy soil- you’re going to have to line your pond. Loam soil allows water to seep between its particles and get away from your pretty little pond.
Should Your Pond Depth Change in Colder Climates?
If you’re living in a colder climate- somewhere north of the Mason-Dixon line, no doubt, you’ll know that when winter comes, ponds and lakes tend to freeze. And when ponds and lakes freeze, fish have to retreat to their lower levels to get away from the cold.
If your pond doesn’t have these lower levels- well, you can imagine how that will go. Fish without deeper levels to migrate to during cold seasons will most likely become fish-cicles by Christmas.
To prevent this awful fate, try digging your pond a little deeper. Usually, a depth of 3 feet or more will be enough to keep your fish safe during the wintertime. Keep in mind, though, a pond can’t just be a 3-foot deep hole. As you increase your depth, you’ll also want to increase your width.
The Advantages of a Garden Pond
It may seem like quite a chore to build and upkeep a garden pond, but whatever difficulties are involved in building a garden pond, there are plenty of advantages that work to outweigh them. So don’t shy away just because of the depth- get cracking and make an investment that will hugely increase your quality of life.
For one, even if you’re not fishing out of a pond, it can be the best investment you ever make. Ponds are a great place to retreat to after a long day at work.
And one little secret only country folk know- is that they sing at night.
Ponds are constantly alive with the sounds of bugs and little fish. Having a pond in your backyard affords you the unique opportunity to watch a whole living ecosystem go about its daily business. From watching as tadpoles turn to frogs to seeing fish do their daily scavenging, you’ll be able to enjoy the liveliness of a garden environment that a lot of people don’t get to experience in their lifetimes.
A garden pond also gives us great life lessons. Seeing the animals and plants- who live shorter lives than us- come and go reminds us that our lives aren’t endless and that we should take advantage of the time we have on earth.
Also, garden ponds just look cool. If you’re a painter or a drawer, you’ll love sitting out by the garden pond come nighttime, watching as the fish poke their lips out of the water and the reeds sway in the breeze.
Oh, and about those reeds- some of them are actually edible. Yes, you’ve probably accounted for the fact that you can sometimes fish out of a pond, but did you know that they’re an excellent source for other edibles as well?
Cattails are a personal favorite of mine. I remember- growing up on my grandfather’s farm, we had three little ponds laid out on opposing ends of the property. Every few days, I’d go down with a net and a basket to catch frogs and cut cattails for lunch.
Cattails are those big, almost five-foot high plants with the long green leaves shooting up into the sky and one big hotdog-looking ball of fuzz on the end. While they may look like weeds, they’re actually edible.
To eat a cattail, simply pull it up, wash off the other husk, and cut off the bottom white part- which tastes somewhat like a sandy cucumber. They’re great boiled and fried.
And that’s not to mention all the other edibles- frogs, fish- but not algae. Pond algae is toxic- keep it off your plate.
All in All
Hopefully, you now have the knowledge and desire to go out and dig your very own garden pond. Your average pond- for warmer climates, will descend to about 2 feet deep, whereas in colder climates, you’ll want to give the fish 3 feet leeway to get away from the ice in winter.