Materials for your
Water Garden

by Joel Police
New Haven, Indiana USA

A wonderful aspect about water gardening is that your imagination and budget are your only limitations. You can convert virtually any item that holds water into a water feature or tub garden. Kits enable homeowners to convert almost anything into a spitting, bubbling or splashing fountain. In addition, many manufacturers market preformed plastic liners that drop into diverse pots, tubs and barrels to create instant water features.

Of course, you can stick with traditional items like a half whiskey-barrel, bathtub, sink, pottery or metal container such as a livestock tank. Each item has its own pros and cons, but nearly any item can work with a little ingenuity. Regardless of the vessel used to hold the water, the true beauty comes from what you grow in it. Before deciding what container to use, mull over a few factors.

Plastic containers or drop-in liners combine the best of safety and convenience. Modern plastics are fish-safe and stand up to the environment well. Once you find a unit that fits the shell you pick, building a water feature with a preformed unit is quick. The downside is that the manufactured dimensions limit you size wise. Plastic units require little care and often withstand winter exposure without damage from freezing. However, if the shell is susceptible to cracking or damage from ice expansion, drain and store it in the basement or garage until spring.

Pottery or concrete bowls and containers offer an array of style and color. You can easily incorporate them into existing landscape settings. Usually, the only modification required for pottery is to plug the drainage holes. Some concrete pots absorb water over time; this can stopped by painting the interior with fish-safe waterproofing paint. Depending on your climatic conditions, you may have to drain and store pottery or concrete in winter to protect it from cracking.

Metal containers such as watering cans and washtubs make great water features. Take extra care when running electrical cords over rough metal edges. The biggest concern with metal containers is rust. Most useable metal containers are tin or galvanized steel treated to make them rustproof. As with concrete containers, it may be beneficial to coat the interior of metal containers with fish-safe waterproofing paint since seams sometimes leak. Copper makes a fabulous medium to work with, due to its rust resistance and the patina it develops. Avoid copper if you want to raise fish. Copper containers and copper fountain units leach copper into the water, which can reach levels toxic to fish.

Lumber and concrete blocks give structural support for container gardens and water features using flexible liners. Select pressure-treated lumber, composites, cedar or redwood because they withstand the weather. Concrete blocks, either the grey building variety or segmented retaining wall blocks, are sturdy and weatherproof. Talk with a construction expert before choosing either wood or block.

The advantage of using wood or block combined with a flexible liner is that you can produce almost any shape and size of enclosure. Make custom-built containers part of a deck; incorporate them into an existing wall or other architectural feature. Wood usually costs more than block per unit of pond surface area. However, it does facilitate designs that are more intricate. When picking a material, consider your experience working with that material and your available tools.

Many water garden centers employ concrete blocks or wood timbers for display ponds because of their quick construction and durability. Even on larger projects, wood and blocks offer great potential. Factors such as humidity, termites and freeze/thaw cycles influence your choice; either material can perform successfully in most environments.

If your project involves a water garden or a koi pond, then choose between rigid and flexible liners. Your liner material choice affects other areas of construction. Rigid liners allow little or no flexion from water or ground pressure. At the other end of the spectrum, flexible liners move with the substrate they line. Rigid liners include plastic, fiberglass and concrete formulations while flexible liners encompass PVC (polyvinyl chloride), vinyl, EPDM (ethylene propylene diene monomer) and butyl products. A composite liner, spray-on urea liner, blends the best features of both.

Nearly everyone has seen the ubiquitous preformed pond unit. Once the mainstay of the hobby, preformed fiberglass and plastic shells come in many shapes and sizes for the homeowner to create a little oasis quickly. Marketed as easy-to-install without the hassles associated with liners (tears, punctures, roots, etc. . .), preformed units enable anyone to create a water garden in an afternoon.

When choosing a preformed unit, the tradeoff is ease of installation versus design constraints. Preformed units can be hard to disguise and naturalize, but for those not interested in an advanced setup, they are just the thing.

The biggest concern for fiberglass and plastic is temperature and frost depth. Plastic preformed units flex and deform more than fiberglass units do during freezing weather, especially where ground heave occurs. Flexing sometimes prevents damage, but in extreme conditions, cracks or creases may damage plastic and fiberglass structures. Both materials weather well over time and quite often outlast the pond itself.

Plastic and fiberglass units are fish safe. Complement them with various preformed stream and waterfall units. They readily accommodate filters, fountains and other accessories. The cost of preformed units is significantly higher than using a similar sized flexible liner, but many homeowners choose preformed ponds because they find them easier to install. Less common rigid liner structures include metal or plastic livestock tanks, children’s swimming pools and concrete structures.

By far the most complex and expensive type of rigid liner is concrete. Yet you can easily justify the expense when you consider the value of show-quality koi that thrive in properly built concrete koi ponds. Modern concrete koi ponds use fiberglass-reinforced concrete to add flexibility and tensile strength. Flexibility helps to prevent concrete from cracking.

While very similar to swimming pool construction, concrete koi ponds have some unique characteristics of their own. The plumbing and filtration systems dwarf that of a pool and water flow rates are much greater. Without the benefit of chlorine and other chemicals to combat algae, UV sterilizers and clarifiers work in conjunction with the latest bio filtering technology as opposed to sand or bead filters common in swimming pools.

Materials used for concrete construction typically entail reinforcing grid or mesh, the concrete itself and various plumbing, electrical and filtration components. Apply concrete with either a wet gun technique (Shotcrete) or a dry gun approach (Gunite). This oversimplifies the process; for most homeowners I recommend leaving the installation of concrete koi ponds to professionals.

Shotcrete and Gunite facilitate creative design opportunities. Many better-quality contractors construct realistic looking rocks and waterfalls with these systems. Natural stone is expensive; a Shotcrete or Gunite waterfall makes a cost-effective alternative to quarried stone. You can use concrete in unstable soil conditions unsuitable for liner ponds.

Concrete ponds necessitate a significant outlay, especially considering the filtration, heating and plumbing associated with state-of-the-art koi ponds. Nevertheless, this cost pays off taking into account their life span, no concerns over liner damage, superior design capabilities and the fact that most concrete pond owners also have a substantial investment in their prized koi.

As with other material types, there are always concessions to make. Besides the high initial investment, the other downside of concrete is potential for cracks. The scale and scope of concrete koi ponds also rule out most homeowners tackling the task themselves. Perhaps the biggest negative for many with concrete is not the cost, but its permanence. Typical pond owners modify their ponds approximately every five years. With concrete, once you make the pond, it is not cost effective to redo it on a regular basis.

In contrast to the permanence of concrete ponds, flexible liners take into account the ever-changing nature of water gardens. By far the most popular choice today, flexible liners give builders the option to fashion almost any shape and size of koi pond or water garden. The most significant advantage of flexible liners is their versatility. Flexible liners cannot compensate for poor planning or sloppy excavation work. However, they are excellent materials for most applications. This category of liners includes PVC, vinyl, EPDM and butyl.

All About Flexible Liners

After deciding the basic structure or “shell”, the next material to consider is tubing or pipe. Many factors influence the plumbing that circulates water.

All About Pipe

One material often glossed over in the materials evaluation process is the stone used for coping, waterfalls and streams. Many factors influence your selection of stone. For instance, natural limestone can raise water pH and become algae-covered quickly. Sandstone breaks down and distributes fine sand sediment in the pond. This damages ball bearings in direct drive pumps. Avoid flagstone that shales heavily; it tends to crack and fracture easily, especially in sub-freezing regions. 

Composition is not the only thing to contemplate when selecting stone. The shape of the stone is also instrumental in achieving the proper look and sound. For instance, using natural fieldstones or round boulders results in an entirely different looking and sounding waterfall compared to one using granite slabs. Stone size and shape also dictate some elements of pond excavation and can influence other material choices. For example, using extremely heavy stones on PVC liners or 20- mil (0.05 cm) EPDM liners may result in liner damage, even with proper construction techniques. Evaluate how well stone stacks and interlocks when building waterfalls, ledges and coping. Stone that leaves large voids and fits together poorly requires additional work and material. Properly selected stone hides the liner, creates a captivating waterfall and specifically contributes to a pleasing water feature.

After the major decisions, turn to the finishing touches. These include fake rocks to hide hardware like filters, skimmers and electrical boxes. Many component manufacturers offer lids and other covers to hide mechanical parts of a water feature. You can readily find fake rocks or “boulders” at home stores or online. Modify fake rocks to match the color and texture of other stones you use in your water feature.

Other finishing touches include gravel or aggregate for streams, waterfalls, edging and filling in voids and spots between the stonework (no discussion about gravel on the pond bottom in this article). Choose an aggregate type in conjunction with picking a stone for coping and the waterfall so that everything matches. Nothing makes for a more unnatural water feature than using one type of stone for the coping, another for the waterfall and still another color or type of aggregate for finishing touches.

Finally, expanding foam and fish-safe silicone sealers keep the water where you want it. Avoid expanding foam designed for residential housing applications. Significant differences exist between pond foam and foam products for the house. Good quality pond foam remains flexible when cured and offers a higher level of UV protection than housing products. Foam products do not withstand long-term UV exposure. Paint any pond foam exposed to direct sunlight.

Avoid using pond foam as a “fix all” solution for poor construction work. Pond foam exists to fill voids, not to hold stone in place, fix holes or to glue the liner together. Good pond construction minimizes the use of foam and uses it only as a finishing detail, not as a component of construction.

A final material to keep on hand is fish-safe silicone to seal flanges, hardware and other fittings on skimmers and filters, depending on the type and manufacturer of the component.

Before purchasing any material, research first and buy later. Compare more than just price; in the end, quality, performance and warranty coverage are priceless. Beginning ponders often tell me about how expensive professionally built water gardens and koi ponds are. They rationalize that pond kits from big box stores are so inexpensive, they can afford to replace pumps and liners every year if they have to. Many builders fail to explain the cost of lost time and maddening frustration from repairing or rebuilding a water feature, water garden or koi pond built with cheap materials. Good materials cost more, but the compensation of enjoyment over the years more than justifies the expenditure.  

All About Flexible Liners | All About Pipe

Waterlilies | Lotus | Aquatic Plants | Victoria | Our Adventure With Victoria
Water Gardening | Water Gardening Friends | New This Month
Kit & Ben Knotts | Our Garden | Search The Site | Home 
Email Discussion List | Site Map
Water Gardeners International