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Best Advice Tips & Tricks for DWC Floating Raft System Aquaponics

The Advantages of Different Aquaponics Systems

Deep water culture aquaponics is a type of aquaponics that utilizes deep channels of water to feed and nourish plants which float atop the water on rafts. The main advantage of DWC that differs from other aquaponics setups is the consistent flow approach that forces nutrient rich and aerated water through the roots of the plants on a 24/7 basis.

If you’re completely new to DWC and have little knowledge on what the system involves and how it works, check out our Introduction to Deep Water Culture Aquaponics article to get up to speed on the basics regarding the technique.

Another advantage of a DWC is that the systems can be configured in various ways; offering setup solutions for a number of different scenarios, including a

DIY home system that doesn’t require electricity, or a highly efficient powered system suitable for compact spaces, or even larger, scalable system ideal for commercial operations.

Furthermore, the deeply submerged roots reduces the risk of the plants developing disease; a welcome benefit that beginners and experts can appreciate alike.

Whilst there are many benefits from running a DWC system, it’s not completely free from compromise. Aside from higher initial costs due to the additional number of components, these parts must also be of the very best quality since there’s little time to rectify problems so failure is not really an option. This also means that your monitoring system and schedule must be extremely effective and strict respectively, since missing any indicators of change can quickly see the system deteriorate.

If it hadn’t already become apparent, the very thing that makes this system hihgly efficient is the exact same component that can cause catastrophic disaster should it fail; the pump. Due to the system requiring a continuous flow to keep the water nourished and oxygenated, if the pump does fail, the whole system will soon succumb to a catastrophic. 

How Deep Water Culture Aquaponics Works

The DWC method itself refers to one three different techniques, each of which provides its own benefits. DWC is typically considered suitable for quick growing plants with short roots, and hardy fish such as tilapia, carp, goldfish, etc, that can survive in relatively low quality water. Deep water culture systems can be configure for both large scale, commercial operations, as well as indoor/outdoor home application.

Components and Parts of Deep Water Culture Aquaponics System

Saves water: This method passes very little water through the plants roots when compared with other aquaponics techniques, and therefore requires much less water. 

Fish Tank: This is where the fish are raised. The tank creates a suitable environment for the fish to thrive and to produce the waste need for the conversion that feeds the plants.

Filtration System: This filers and cleans the water to remove solid waste so that clean water can be recirculated back into the system. DWC filteration systems typically consist of solid separator filters, together with biofilters such as sand, pebbles and limestone. Biofilters are an important part of the system as it becomes home to the colonies of beneficial bacteria.

Grow Beds: These contain the floating rafts that support the plants.

Floating Rafts: The floating rafts themselves; these buoyant platforms are typically made of food-grade materials. They feature holes or pockets in top surface where plants can be grown in net pots. The net pots force the roots to spread out as they grow. This maximizes the plants ability to take on nurtients and oxygen as the roots dangle in the consistent flow of water.

Water Pump: The water pump is the heart of the system. Not only does it create oxygen in the water, it also pumps the water around the system to give life to each component so the system so everything runs in harmony.

Additional Aeration: Should the water pump not be injecting as much oxygen into the system as it requires, you can try adding air stones, and/or additional pumps to increase bubble creation and therefore oxygen levels.

Optional Extra Steps: Setting up the Water Recirculation System

If you wish to build a large commercial system, or start small with the idea of expanding quickly in the near future, taking the additional steps to setup a water recirculating system is likely your best bet.

This technique simply adds another water pump to the setup. This is placed in the water reservoir and works to pump water above the plants, so they can be watered from above. This allows the water to fall back down into the system.

Recirculating DWC systems can help keep oxygen levels, feed distribution, and temperature stable, as well pH and CF levels in check, which all work together to produce much bigger yields.

Best Plants for Deep Water Culture Aquaponics Works

  • Lettuce and other salad leafs
  • Cabbage
  • Herbs such as basil and watercress
  • Cucumbers
  • Cauliflower
  • Strawberries
  • Tomatoes
  • Peppers

Best Fish for Deep Water Culture Aquaponics Works

  • Tilapia: Hardy, easy to take care of and tasty
  • Trout: Easy to feed, good in cold climates, tasty
  • Tetra Fish: Grow fast, good for smaller systems
  • Sunfish: Tolerate temp changes, good with other fish, taste great
  • Catfish: Good tolerance to temp changes, good with other fish, also delicious
  • Koi/Carp: Resistent to parasites, tolerant to temp changes
  • Goldfish: Hardy, tolerant of pH and temp changes, good as sacrificial fish for first timers
  • Murray Cod: Hardy, long lasting, handles fluctuations in temp and pH
  • Artic Char: Another great for cold climates, good for large tanks, easy to source
  • Prawn/Shrimps: Grow quick, minimal maintenance, extremely delicious
  • Guppy aka Million Fish or Rainbow Fish: Hardy, good with other fish, tolerant to pH and temp changes
  • Bluegills: Tolerant to temp changes, eat vegetation and algae, low maintenance, recent explosion in popularity for eating
  • Perch: Extremely tolerant and hardy, good with other fish, very tasty
  • Bass: Eat almost anything, taste great

Best Location for Deep Water Culture Aquaponics Works

Although aquaponics setups are essentially creating its own environment, the location in which you choose can still have a large affect on your ability to maintain consistent  , safe temperatures. Unless you’re prepared to construct a fully climate controlled unit to house the system, aquaponics will always be susceptible to external elements, therefore your location in the world, as well as the setting you choose, should both be taken into consideration when planning your system.

When it comes to your locations climate and how it will affect your DWC, the considerations are fortunately quite logically. Plants like stability comfortable climates that aren’t too extreme. You’ll also need to ensure light exposure is under control since light is essentially the fuel plants use to photosynthesis. Once you’ve set optimal conditions you’ll then need to monitor things regularly, and be acutely aware of when changes show that it’s time for you to act.

Factors to Consider Regarding Location of Your DWC Setup

Sunlight: This is one of the major factors; plants require at least 6-8 hours of sunlight a day for optimal photosynthesis. Dark periods must also be dark and free from light pollution so as not to mess up this schedule.

Shelter: Since aquaponics systems contain living organisms they function best in temperate climates that are neither too hot nor too cold. Consider providing additional heat in cold environments, or shade from the sun/lights/heat sources, as well as ventilation to aid in cooling.

Reliable Electricity: Aquaponics die quickly if power is cut and/or the pump stops working. This causes the water to be insufficiently aerated, filtered and cleaned, which can result in devastating consequences.

Reliable Water Source: A reliable, consistent supply is essential. Furthermore, the water source should be free from chlorine, and stable; i.e. not susceptible to random contaminations or fluctuations in flow.

Monitoring and Adjusting Water Quality Parameters

Water Quality: Constant monitoring of water quality parameters will allow you to make important adjustments the moment you see any unexpected fluctuations in levels. This is essential for the health of the plants and fish, because without such care and attention, you may see the collapse of the ecosystem in a very short timeframe.

To sufficiently monitor vital levels in the water, you’ll need to test for:

  • pH
  • Ammonia
  • Nitrites
  • Nitrates
  • Dissolved Oxygen DO Levels

Should any of these levels fall out of acceptable ranges, you’ll be able to bring things back into symbiosis by adding or removing fish; adjusting the feeding amount or frequency of the fish; adding nitrifying bacteria to aid the conversion; adding more surfaces for bacteria to colonize; adding or removing plants; aerating the water more; or changing a part of the water.

Water Temperature: Water temperature is another factor that must be kept with specific ranges so both fish and plants can survive. It’s also important to keep the temp within range has high temps can reduce the levels of dissolved oxygen, and lower temps will stunt the plants growth. These ranges vary depending on the chosen species but will typically be advised to be between 18 to 22°C or 64 to 72°F.

Should you find the water temperature fluctuate either side of this range then you can use heaters or coolers to make the water warmer or cooler and bring it back within a safe range.

pH Levels: pH Levels of the water are important in creating optimal nutrient availability and uptake for the plants, as well as a safe, suitable environment for the fish. 

This range will depend in large part on the species of plant. Most thrive in a slightly acidic to neutral pH range (around 6.0-7.0), whereas most fish typically enjoy slightly more alkaline levels between 6.5 to 9.0 pH. Therefore a compromise is often made to keep levels between 6.8 to 7.2 pH

Nutrient Balance for Plants: Monitor nutrient levels on regular basis, multiple times a day if possible, at least once otherwise; check nitrogen, phosphorus, and potassium, in the water. Adjust the fish feeding and supplement nutrients as needed to maintain a balanced plant nutrient profile.

Fish Health: The fish themselves can be indicators that the system is unbalanced, and/or something is wrong. Observe the fish for signs of stress, illness, stress, or abnormal behavior.

Any health issues you spot should be taken care of promptly; often times simply replacing the fish can help, however it may not address the underlying cause. In cases where you’re unsure what’s at fault, it’s recommended to consult a veterinarian for more information.

Other Key Factors To Monitoring DWC Aquaponics

Clogging: Excess fish waste, debris and/or roots can clog the grow bed and plumbing system, which can impede water flow and nutrient distribution. Keep the system clean will help mitigate this problem.

Oxygen Levels: Insufficient aeration can lead to fish getting stressed or root rot in plants, to avoid this ensure adequate oxygen levels are created so both fish and plants can thrive.

Algae Growth: Excess algae can start to compete with fish and plants for the nutrients in the tank and grow beds; this can lead to water problems as the system becomes unbalanced. Sunlight is a factor that cause algea to grow; another reason why controlling light exposure is extremely important.

Pump Failures: As previously mentioned, the pump is the heart of a DWC setup, it’s responsible for circulating the oxygenated, nutrient rich water through the system to keep the plants and fish alive. If the pump fails, oxygen levels drop immediately, nutrients are no longer converted and the water becomes toxic.

Pest Prevention: Pest infections can be a problem. They often occur due to the introduction of contaminated plants, or from uncleanly practices. Preventive measure are always best here, this can be achieves using physical barriers or organic pest control methods.

Harvesting and Replanting

Both of these processes are essential to the health and longevity of your aquaponics ecosystem. The yield is essentially the main goal of running such a system, and is therefore typically top on a growers’ list of things to get right. 

Harvesting: Harvest plants only when they reach maturity; that is, when they reach the desired size and after the advised vegetation/flowering period.m Be sure to use sharp, clean tools as they’re not only safer for the plants but also safer for you. Most blade injuries are caused from dull blades that slip off the item being cut. Clean tools also help avoid contamination.

Replanting: Replanting is crucial to keeping the system cycling in a healthy manner. It’s advised to plant seeds in a staggered schedule to ensure a continuous supply of fresh produce. You’ll also need to adjust nutrient levels based on the requirements of the new plants; this will ensure optimal growth and productivity in the coming cycle.

In Conclusion

Deep water culture, or floating raft, aquaponics are an ideal solution for both home or commercial application. Offering setup options that be configure to maximize space, or designed to support as many plants as possible, these systems yield highly efficiently for its footprint, and the easy setup, operation, and reduced risk of developing disease makes the method great for beginners, or any one who wants to setup an aquaponics system.

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