How to Prevent Clogging in Ebb and Flow Systems? (3 Solutions)

Is your ebb and flow system draining slow? If you suspect that your system is clogged, here are some suggestions on how to solve it and save your plants from drowning!

Clogging in an ebb and flow system is caused by 1) excessive root growth, 2) algae accumulation, and 3) debris. It can easily be prevented and solved by regular cleaning, root pruning, proper spacing, and thoughtful design of the system.

Having an Ebb and Flow system is often a step up from a beginner’s Kratky or Deep Water Culture (DWC) system. For water to pump up and drain down efficiently, the pipes and two separate containers must have clear drains that are free from roots, algae, and other blockages.

What Are The Effects of Clogging?

Clogging occurs when root growth, algae growth, debris, or other factors prevent or reduce the inflow and outflow of water. In an ebb and flow system, this can result in 1) blockage, and 2) reduced water flow.

Clogging negatively affects plants because it may cause plant disease or death by drowning. Hence, it is important to know the negative effects of clogging on the system and how these will affect your plants.

1 – Blockage

Blockage occurs when pipes filling or draining the flood tray are completely blocked. This will either drown and starve the plants because the system cannot effectively drain or flood the tray with the nutrient solution, respectively.

Blockages are extremely detrimental to an ebb and flow system compared to other hydroponic techniques because bringing nutrients and oxygen are separate processes – flooding and draining, respectively.

If the drain is blocked, the flood tray will overflow. If the pipe for the water pump is blocked, the nutrient solution will never reach the tray.

2 – Reduced Water Flow

Reduced water flow occurs when the pipes are not completely obstructed but exhibit reduced inflow and outflow of water in the flood tray. This will not kill the plants but may cause degradation of plant health.

Though not as destructive as pipe blockages, reduced water flow can ruin the flood and drain schedule of the system. A consistent schedule is important since it makes sure that the roots will receive oxygen and the nutrient solution at an even pace.

Causes, Prevention, and Solutions to Clogging

Clogging is caused by 1) excessive root growth, 2) algae accumulation, or 3) debris. It can be solved by deep cleaning. To prevent this problem it is important to 1) prune overgrown roots, 2) paint the system to prevent algae growth, and 3) use compact, inert media to prevent debris from forming.

Clogging is a relatively simple problem to solve since it will mainly involve cleaning and scrubbing the pipes of debris. Prevention is more complicated because it involves an opaque, well-spaced, and thoughtfully engineered system.

1 – Excessive Root Growth

Excessive root growth can go through the inflow and outflow pipes, resulting in blockage and reduced water flow.

It is a fact that hydroponic systems exhibit longer, whiter, and healthier root systems compared to soil cultivation. However, this can turn detrimental when there is not enough vertical space between the plants and the flood tray in an ebb and flow system to contain the root system.

Prevention: There should be enough vertical space between the bottom of the flood tray and the root system. The inflow and outflow pipes should be spaced away from plant roots. Finally, larger outflow pipes may be more desirable if they can be sourced and implemented.

Solution: Pruning the overgrown root system and pulling out roots that got into the pipe will solve clogging. Preemptive pruning can also serve as a preventive measure as well as a solution in this case.

2 – Algae Accumulation

Algae accumulation can clog pipes and live freely if the system is exposed to light and warm waters. Algae may cause blockage, reduced water flow, and competition for nutrients in the system.

Algae accumulation is a matter of fact for hydroponic systems since they are simple organisms that thrive on warm, nutrient-rich, and slow water. Algae benefit from the nutrient reservoir or the flood trays. They are particularly detrimental because they consume nutrients and oxygen in the system that is meant for plants.

Prevention: Painting the covers for the grow tray, nutrient reservoirs, and pipes is an easy technique to prevent the sunlight from entering the system and promoting algae growth.

Distilled water may also reduce the likelihood of algae growth since it is sterile and pure. A water chiller may also be an option since it will make the water in the system inhospitable to algae.

Solution: Drain the system of all water and apply either hydrogen peroxide or chlorine bleach solution. Wearing the proper safety gear, manually scrub the affected areas with a flat scrubbing brush for the surface and a cylindrical scrub for the interior of the pipes.

3 – Debris

Debris and dirt often come from the growing medium used in the system. Thus, when it eventually chips, breaks, or falls off, debris and dirt will accumulate and lead to reduction or blockage of water inflow and outflow.

Ebb and flow systems often use compact and inert media that drain well like hydroton pellets or Rockwool that may erode over time. Gardeners using traditional growing media may find them clogging pipes later down the line if their containers have slits or holes on them.

External dirt and debris may be due to a generally unclean growing space so it is best to keep the system indoors or any other clean environment.

Prevention: Flood trays with canal grids are the best for a flood and drain system. It allows the plant containers to be slightly elevated from the flood tray and lets debris accumulate in the canals rather than in or near the pipes.

Using inert media will lessen the likelihood of clogging. If you plan to use alternative growing media that have loose particles, make sure that their containers only have small drainage holes in them so that they are less likely to spill over the flood tray.

Solution: Debris and dirt can be removed with a flat scrubbing brush for flat surfaces and a cylindrical scrubbing brush for the tubes. In this case, liquid soap may be a better cleaning agent because it acts as an emulsifier, easily carrying dirt on its surface.

Picking the Right Parts for the Job

Choosing the proper components in an ebb and flow system helps prevent clogging. High-quality parts lead to high reliability and better plant growth.

Here are just a few key components you should watch out for. I included some recommendations that combine function and practicality.

1 – Flood Tray

The best flood tray for an ebb and flow system is one with a canal grid to better facilitate the inflow and outflow of water.

Flood trays with canal grids are not required to have a functioning ebb and flow system. However, they are excellent in facilitating the inflow and outflow of water by letting the debris accumulate in the canals instead of the pipes. Flat flood trays will still work and placing risers can emulate a canal grid effect.

2 – Inflow and Outflow Fitting

Inflow and outflow fittings are the components responsible for the inflow and outflow of water in the flood tray.

The inflow fitting facilitates the inflow of water into the flood tray. Upon reaching a certain water level, the outflow fitting activates, draining the contents of the flood tray.

HOW TO: Use the Danner Supreme Hydro Ebb & Flow Kit for Gardening

These fittings often come in kits and are designed to allow the gardener to set at which height the outflow fitting will activate to drain the flood tray.

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3 – Water Pumps

Water pumps are an essential component to effectively flood a system. It is recommended to have a pump that maintains 300-500 gallons per hour (GPH) at a 2-4 feet head height.

Always read the GPH rating in relation to maximum head height when purchasing a water pump. The higher the head height, the harder it is for the pump to output the water vertically due to gravity.

For most gardeners, a simple submersible aquarium pump is enough to accommodate the 2-4 feet distance from the pump in the reservoir to the flood tray. For larger systems, an equally larger pump is required.

4 – Air Pumps

Air pumps are still a necessity even for an ebb and flow system. Air pumps should provide 5 mg/L of dissolved oxygen (DO) or more to a system to keep the roots oxygenated.

It might seem redundant to an ebb and flow system compared to other hydroponic techniques since the draining phase will oxygenate the roots, but that may not provide enough oxygen. It is still vital that the roots receive oxygenated water while the flood tray is flooding and the growing medium is wet to prevent plants from drowning.

5 – Schedule Timers

Ebb and flow systems need to be flooded 4-10 times per day depending on the plant grown and the growing medium used. A good timer makes sure that there is a consistent flood and drain schedule.

Many gardeners swear by mechanical outlet timers but we think that digital timers allow for much more flexibility. Digital timers allow for greater incremental settings such as specific flooding and draining schedules every day.

Digital timers might be a bit of a hassle to program but they are worth it for the price and functionality they offer.

5 – Water Chillers

Algae grow best under warm water temperatures to 25-35°C (77-95°F). Water chillers prevent algae from forming by lowering the nutrient reservoir to a consistent 18-21°C (64-70°F).

Gardeners who love micromanaging and observing their systems will find water chillers to be a useful addition to their systems. Apart from preventing algae growth, it also allows a gardener to precisely set the optimal nutrient reservoir temperature for a specific plant, thus, improving growth.

Summary of How to Prevent Clogging in Ebb and Flow Systems

Clogging is caused by 1) excessive root growth, 2) algae accumulation, and 3) debris. Clogging can result in blockages or reduced water flow which may lead to plant health degradation or death by drowning.

Clogging can be prevented by pruning overgrown roots, painting the system to prevent light from promoting algae accumulation, and using compact, inert media to prevent debris from forming.

Any clogging that does occur can be easily solved by cleaning the system with the use of scrubs and cleaning fluids.

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  • “Avoid Harmful Algae and Cyanobacteria” by n/a in CDC
  • “Ebb & Flow Hydroponics Watering Schedule: How Often to Flood & Drain?” by n/a in Leaffin
  • “Algae Corner: What the Film?” by n/a in SePro
  • “Ebb and Flow Hydroponics: 10 Common Questions Answered” by Jamie in WhyFarmIt
  • “How to clear blocked pipes” by n/a in DIY
  • “Analysis of the Algae Growth Dynamics in the Hydroponic System with LEDs Nighttime Lighting Using the Laser Granulometry Method” by Bawiec et al in Water, Air, & Soil Pollution volume 230(17), 2019
  • “Alternative Hydroponic Substrates” by Bridget White in GPN
  • “What size pump should I get?” by n/a in Home Hydro Systems

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