Understanding DWC and Feeding

Originally written in 2022, updated Jan 2026

This article was a cover feature of a 2022 Maximum Yield magazine

How deep water culture works, how to feed it, and how to keep roots thriving

Deep Water Culture, or DWC, is one of the fastest growth hydroponic methods when it is designed and managed correctly. In a DWC system, plants sit in net pots while their roots hang into an aerated nutrient solution. That solution is constantly oxygenated, and in many commercial builds it is also recirculated through multiple sites (often called RDWC).

The reason DWC has a loyal following is simple.

When the root zone has consistent access to water, oxygen, and nutrients, plants grow with very little resistance, and that can translate into aggressive, lush vegetative growth and strong flowering performance.

There is a saying that fits DWC perfectly:

Look at your roots, not your fruits.

If the roots are happy, everything above them gets easier.

Why it is called “deep”

DWC relies on dissolved oxygen. Air stones or diffusers at the bottom of the system push bubbles through the water column. As bubbles rise, they increase oxygen transfer into the solution and keep the root zone supplied.

More water volume can also help buffer the system. A larger total solution volume tends to fluctuate less in:

• pH

• EC or PPM

• temperature

• nutrient balance

That stability is one of the underrated advantages of multi site DWC. Your grow sites become part of the reservoir volume, which can reduce how large your control tank needs to be and can simplify your fertigation room footprint.

DWC feeding is different

Immediate access means easier to overfeed

DWC plants have nutrient solution touching the roots at all times. That is great for growth, but it also means the plant can take up more than you intended if you push the solution too hard.

A good rule for DWC is:

Feed lighter, adjust more often.

Instead of chasing high PPM from early on, many successful DWC growers run a more moderate baseline and only increase feed strength when plants are clearly demanding it, often around peak flowering with strong light and a stable environment.

How to tell if you are overfeeding

A classic early warning sign is:

• overly dark, heavy green leaves

• leaf tips starting to yellow or crisp at the very edges

• leaves that look “thick” or slightly clawed depending on the imbalance

Tip burn is often the first visible symptom growers notice, but remember it is only one signal. Different imbalances show differently, and the best indicator is always the full picture:

• leaf color and texture

• root color and smell

• daily water uptake

• daily EC drift

• pH drift

• plant posture under lights

In DWC, your instruments matter because the root zone is always active.

There is no universal perfect PPM

What actually controls nutrient demand

The best EC or PPM depends on:

• cultivar genetics

• growth stage

• light intensity and daily light exposure

• CO2 strategy

• water temperature and dissolved oxygen

• room VPD and transpiration rate

• nutrient line and ratio balance

That is why rigid one size feeding charts often fail in DWC. Two rooms can run the same EC and have completely different results depending on environment and plant behavior.

A smarter approach is to watch the plant and watch the drift.

Why DWC can reduce water and nutrient waste

But keep the claim realistic

In drain to waste systems, runoff is discarded by design. In DWC, the solution stays in the loop and you manage it.

That can reduce total water and nutrient consumption significantly, especially at scale, but the savings depend on how the facility operates and how often solution is exchanged.

In practice, DWC can reduce water and nutrient waste dramatically compared to drain to waste, often by a large margin when managed well, because you are not intentionally throwing away runoff every irrigation event.

Power outages

Why DWC is often a safer option

One reason commercial growers like DWC is stability during short interruptions.

In a power outage:

• irrigation does not stop because plants are already in solution

• the biggest risk becomes oxygen delivery and water temperature control

How long plants can tolerate an outage depends on many factors, especially biomass, water temperature, and how much oxygen is in the solution. You should never plan your operation assuming you have a long safe window.

Best practice is still:

• backup power planning for critical systems

• quick response SOPs

• restore aeration and circulation as early as possible

When power returns, many operators choose to refresh the solution and re stabilize the system.

Cleanliness matters more in recirculating systems

DWC rewards clean operation and punishes sloppy habits.

A few non negotiables:

• keep light out of reservoirs and plumbing

• control biofilm buildup

• maintain filtration and sanitation routines

• avoid letting dead roots and organics accumulate

• keep water temperature in range with a proper chiller strategy

If the system is clean, it stays stable. If it gets dirty, everything becomes harder.

A note on hydrogen peroxide flushing

Some growers use hydrogen peroxide as part of sanitation or reset routines. It can add oxygen and reduce microbial load, but it can also harm beneficial biology and root tissues if misused. Because concentration and contact time matter, peroxide routines should be applied carefully, and ideally with a plan that matches your cultivation style and your microbial strategy.

If you choose to use peroxide, treat it like a tool, not a habit. And always protect roots first.

Is DWC right for your facility

DWC is incredible, but it is not the best fit for every scenario.

DWC tends to be best when you have:

• strong environmental control and dehumidification

• a plan for water temperature control

• the ability to monitor and respond consistently

• a facility layout that supports serviceability and cleanliness

• enough veg capacity if you want large bush style plants

Tradeoffs to consider:

• larger plants often mean longer veg time and more veg space

• water chillers and plumbing add cost

• system design and redundancy matter more than most growers expect

If you have limited veg space, want a faster simpler install, or prefer a more forgiving learning curve, drain to waste rockwool or coco can be a better starting point.

The takeaway

There is no growing method quite like a well designed, fully automated DWC system. The level of root zone control can produce extremely healthy, fast growing plants and impressive canopy performance.

But DWC only shines when the system is engineered properly and operated cleanly.

If you are considering DWC or want to optimize an existing RDWC room, 4trees can review your layout, plant count goals, and mechanical strategy and help you build a plan that runs stable and performs the way DWC is supposed to.