How Do Ponds and Trenches Fit into Hydroponics?

While some of the original hydroculture experiments and related ancient methods used open waterways for growing, most modern hydroponics systems rely on pre-fabricated tanks, pipes, troughs, and similar containers. For small backyard projects, people have gotten creative by reusing bathtubs, water storage tanks, and even swimming pools into spaces for growing crops. However, relatively few commercial and hobby designs rely on in-ground structures. This is unfortunate because digging in-ground ponds is often far more affordable, longer lasting, and easier to maintain than dealing with above ground tanks. Learn what role in-ground and above-ground structures can play in a hydroponics system and why they should be more widely used.

Replacing Tanks and Pipes

While you can’t entirely replace the plumbing required to connect the parts of a hydroponics system, you can definitely swap out tanks and other bulk water holding structures for in-ground options. In fact, many larger tanks must be partially or fully buried to handle the weight and force of the water. If you’re already doing the work of excavation to prepare for the tank, why not just install a flexible liner that only costs a fraction of the pre-cast tank? Liner can also help reduce the amount of PVC required in a drip or deep water system. Digging in-ground trenches and channels deliver water where it’s needed, even with the use of pumps.

Benefits of In Ground Hydroponics

Choosing to dig in-ground ponds and trenches can pay off, even if it’s a little more work than installing frames and above ground tanks. First, digging an in-ground structure and putting in a flexible liner will generally cost far less than buying a pre-fabricated tank or tub. This is especially true when dealing with large volumes of water over a few hundred gallons. Even when tanks this large are available at an affordable price, the cost of transportation and handling can double or triple the final price. Durable liner materials like reinforced polyethylene (RPE) are thin and light despite offering high tear resistance. This means that everything from shipping to installation is cheaper, easier, and more likely to succeed. Other possible benefits of choosing in-ground ponds for hydroponics include:

  • Free insulation from the thermal mass of soil, preventing temperature swings
  • Reduced chances of water loss due to collapse or leaks, as long as you choose the right liner
  • Food safe liner materials like RPE are often more widely available than pre-formed rigid liners or tanks
  • In-ground water features are just as easy to plumb and connect to pumps as above-ground tanks
  • Savings on expensive framing and supports that can handle the weight of the water, which can cost as much or more of the tanks themselves.

Designing Ponds and Trenches

Ponds for hydroponics are easily sized for the needs of the system in the same way you’d determine the size of freestanding tanks. If a certain number of crops would require 500 gallons of water to supply a deep water culture system, that amount stays the same whether you’re working above or below ground. Of course, you’ll need to do some extra work to figure out the dimensions of a pond rather than just ordering the appropriately sized product. Use a pond calculator and start with the desired depth required for your particular system. Over-sizing hydroponics vessels and units by 10% to 20% is recommended regardless of the system you choose in order to create a buffer to prevent overflows.

Building in Access to Equipment

It’s tempting to bury pumps and plumbing along with tanks or ponds as you’re designing and building your new hydroponics equipment. It may seem like putting them underground can protect them from damage, especially during winter when freezing temperatures can burst pipes and damage pumps. However, underground fixtures are hard to reach and even harder to fix. All hydroponics equipment requires regular maintenance due to the growth and build up of algae. Putting pipes under concrete or soil is just asking for a clog that shuts down the entire system until you dig everything up. Leave all the connecting plumbing and related equipment exposed and rely on pipe insulation instead.

Above Ground Raceways Built from Scratch

Raceways are long and narrow channels first designed for raising fish species that need constant water movement, such as trout. They also work well for deep water and drip hydroponics. If you can’t dig into the ground or want to build a custom hydroponic system over a concrete slab, consider building custom above-ground raceways. Lumber or metal frames support a durable liner, such as AquaArmor from BTL Liners, to create custom raceways and tanks of any size. Decide on an ideal raft size or the volume desired for a drip system, then size your above-ground structures to these measurements for easy design.

Why Do Ponds and Trenches Need Liners?

Building custom hydroponic fixtures is only an efficient way to design a system if you use the right lining materials. Unlined ponds lose too much water through the soil surface. Even the thickest clay soils feature tiny pores between the particles that allow water to escape over time. When you’re trying to make efficient use of a rich nutrient mixture and a limited supply a water, you can’t afford to lose both to seepage. Liners also prevent soil from getting destabilized and washing away. If there’s a high water table in the area, you’ll also find that water can enter the pond and weaken the desired nutrient levels. A liner prevents this from happening. Finally, liners are also essential to prevent scouring and erosion in channels and trenches where water is moving at any speed.

Don’t feel locked in to using just in-ground or pre-made aquaponics equipment and designs. It’s fine to mix and match different styles of growing in the same system, as long as they’re adjusted to work together. Starting with in-ground ponds and trenches for the reservoir and processing tanks is often easier than using them for everything. If you’re ready to add more in-ground features to your space, check out the flexible RPE liners here at BTL Liners to find the right material.


Liners by BTL

AquaArmor Pond Liner

The most versatile liner on the market today, AquaArmor maximizes protection from harmful UV rays, tear resistance and punctures that cause leaks. Simply the best liner on the market.

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