How to Build a No-Dig, Pump-free Pond
Updated: Jan 17, 2022
In September, we scored two huge concrete planters that had been discarded in an industrial rail yard. The first thing we did was select locations for the large containers. The first one was placed in a prominent corner of the pool; where we would have a view of it from the screened patio. The second one was placed within a mulched bed by our front door; in a location that receives a significant amount of rainfall runoff from our roof. It receives so much runoff, in fact, it is like a waterfall every time it rains (no gutters). So, the second one needed to fulfill a practical role as a miniature stormwater basin to prevent the bedding plants from getting pummeled. The family immediately voted to transform the poolside planter into a functioning pond!
If you can find a large container that doesn't have drainage holes, or that can fit a bathtub rubber drain stopper, then converting it into a pond will be cheap and easy. I have seen people reuse old bathtubs for a whimsical look, or build their own no-dig ponds by building up walls with concrete blocks and draping pond liner over them. I think using a large planter can be more decorative; a large planter that is short and wide would be best. Sometimes planters come with a removable rubber stopper for the drainage hole too.
Our first order of business was to level the containers and make them leak-proof. We ended up using two different methods to achieve this. The poolside pond was sealed with Flex Seal products (linked below). According to the manufacturer, once it is cured, it is safe for plants and animals. Following the manufacturer's directions, I cut three strips of Flex Tape and laid them across the hole in the shape of an asterisk (*). Then, we sprayed two coats of Flex Seal spray over the tape, making sure to overlap the edges of the tape (we already had this spray in our stash and I was glad to finally use up the end of the can). It worked! These are the Flex Seal products we used:
The plan is for the front door pond is to act as a rainwater collection basin. This pond will not have any fish or plants, so only time will tell how well it performs this function. My husband added a light and thread it up and through the drainage hole, so wires wouldn't show on the outside of the container. We tried the Flex Seal method again, using the last bit of spray in the can, but it didn't work over the electrical wire. After much testing and tweaking, the pond kept slowly leaking. We decided we wanted some wiggle room with the lighting anyway, so the wiring came out from the bottom of the container and a more permanent sealing option was employed (pictured below). He used hydraulic cement and that worked like a charm. No more leaks! He draped the electrical wire over the side of the container and painted it so it would blend in better with the concrete (the landscape plants will also help once they fill in). Now, we have multiple programmable color options to offer a little surprise to guests at the front door. I will need my husband to write a DIY landscape lighting blog post in the future! Here is a link to the cement we used:
Once the container is sealed, you may want to fill it with water and let it sit for at least 24 hours. This will allow chlorine in your municipal water supply to degrade before adding any plants or fish. Now, you may have noticed in the title of this post, that we are building a pump-free pond. If a natural waterbody can function without a pump or filter, then certainly our manmade pond can function that way as well... right? The trick is, a natural waterbody has plants, animals, soil and water all living together in harmony. A beautiful, natural-looking pond with clear water is a system of checks and balances. The biological processes of defecation and death add nutrients to the water in the form of detritus, the decomposition of organic material. So, what about algal growth and mosquitos?! Algae loves heat, light and nutrients; but we don't want our pond to be a stinky, green mess. Mosquitos love standing water, but we don't want it to become a breeding ground for mosquitoes.
The following are my tips for setting up a well-balanced, pump-free water garden:
Add fish slowly. We started with a handful of guppies, and inadvertently received some brine shrimp and snails as well. Brine shrimp are a source of protein for fish, and snails help keep algae at bay. After a couple of weeks of monitoring, another round of fish were added to the pond. Going to the pet shop and picking out fish became a favorite activity for my husband and daughter. However, for the greatest success, choose healthy, hardy fish that can tolerate your region's climate. Also, be aware of the mature size of your fish; ask the sales associate how much space the fish needs. It's important not to buy more fish than your pond can support. Another note: after a few months, we were able to stop feeding the fish altogether. Our system had achieved some balance, and the fish were happily breeding & consuming whatever they could find naturally.
Add plants in layers. First of all, plants that grow best in your climate, or better yet, native plants, will be the easiest to care for. Plants are a must because they will outcompete algae for space and nutrients, and help oxygenate the water. Once you have a good mix of animals living in and around your pond, you won't need to fertilize the plants. For the most natural look, utilize plants in different zones. In a natural waterbody, the littoral zone is the zone closest to the shoreline and where the sunlight reaches the bottom; this is a good zone to mimic for your pond. Choose plants from the following littoral zone categories: emergent and floating. For my climate, I chose tropical water lily as my floating layer, and Equisetum hyemale (common name: scouring rush or rough horsetail) as my emergent layer. Emergent plants have most or all of their vegetation above the surface of the water, so I used old landscape bricks to prop up the plant in the center of the pond. The water lily doesn't necessarily need soil, but it does need to be weighed down, so small stones in a plastic pot were used. The lily's floating leaves provide habitat and shade for the fish, while the horsetail provides a perch for dragonflies (by the way, they eat mosquitoes!). Some other plant options for south Florida include species in the genus Cyperus, Iris, Bacopa, Alocasia, or Colocasia (among others), golden canna, aquatic milkweed (Asclepias perennis), pickerelweed, American lotus, sedges and rushes, or the red sealing wax palm (Cyrtostachys renda)!
Diversity is key. Think about the way nature works in harmony without human intervention. Remember: checks and balances! A diverse population of plants and animals will help keep the nutrients controlled, which is the most important (and most difficult) thing to do. This principal should apply to the garden as a whole as well. It took our pond about a month to establish a breeding population of guppies (when there is breeding, you can pat yourself on the back!).
Support the microorganisms. Simply put, this can be done by providing extra surface area for organisms, and by leaving some dead plant material to sink to the bottom. The plant material at the bottom will undergo what is called anaerobic decay, or decay in the absence of oxygen. You know that rotten egg swampy smell? Yes, that is anaerobic decay; but you're unlikely to stir up the water and release that smell from your pond (ours doesn't smell at all). Some decay encourages healthy fungi and bacteria to grow. When building up the pond, I stacked leftover bricks and landscape pavers in it. Not only do they add surface area for organisms to attach to, they provide a shelf to prop up the plants and hiding places for the fish. I also placed native limestone chunks at the surface-level of the water, which help to provide extra habitat, a landing pad for birds, and a more natural look.
Make Observations. Every day, when my daughter has her 10 a.m. break from virtual school, she goes out and checks the pond. We also check the pond as a family every night. We are enjoying the pond, yet monitoring its health at the same time. When you properly monitor the pond, you can make adjustments quickly before big issues occur.
A Few Other Notes:
Of course, no matter how hard you try to get everything perfectly balanced, life happens... In that case, I recommend the following eco-friendly products to use as a spot treatment, should you need it:
We have yet to have any issues with the front door rainwater collection basin (which doesn't contain any fish or plants), but then again, we are heading into the cooler fall and winter months here in south Florida. I suspect when the weather starts turning very hot and dry (towards April and May), that we will have to utilize some chemical control methods. Some other options for preventing algal growth are to paint the interior surfaces of the basin with black epoxy or use special pond dye to reduce the amount of UV light that reaches the bottom (this may work during the dry season). If algae becomes a problem in the basin, transferring some of the aquatic snails from the poolside pond might also work. In the summer, since there is so much rain continually regenerating the basin with fresh water, I don't suspect we'll have much of a problem then. What I'm trying to explain is... nothing will be constant! These ponds will experience seasonal changes, just like the garden. It's best not to sweat it too much and think of it as a fun science experiment. Our family has really enjoyed the addition of the ponds to our yard!
I also want to point out that some tropical aquatic plants grow VERY quickly! For example, in one month, I have already propagated about 10 more waterlilies from the one that I purchased. And remember, if the plants get out of control, just compost them. Never release any plants or fish into a body of water like a canal or lake. The state of Florida spends hundreds of millions of dollars a year trying to control invasive plants and animals, many of which were released from the pet trade.
If you decide to build your own pond, tag me on social media! I'd love to see it!