Comparing hydroponic setups: DWC vs. NFT

The type of hydroponic growing system matters most when you’re comparing different types of vertical farms. 

There’s many types of hydroponic farming systems like nutrient film technique (NFT), deep water culture (DWC) and ebb and flow. All these systems deliver nutrient-rich water to the plants in different ways.

By the end of this blog, you’ll better understand the different types of systems and their advantages and disadvantages for you as an operator. 

But first, a caveat, no system is perfect. What one operator finds easy, another might find difficult. You will always have to tweak your system so it works best for you. 

Don’t want to wait? Grab the entire vertical farm comparison series as a PDF here.

SUMMARY

• Deep water culture (DWC): plants sit on floating rafts under lights with their roots in nutrient solution.

• Nutrient film technique (NFT): plants sit in gutters with a shallow nutrient solution that flows by plant roots.

• A DWC system offers more reliability and temperature stability because roots are always submerged in water.

• However, maintenance for a DWC and NFT system looks different. Cleaning in a DWC system is easier but you have to do it more often.

• Because you have more water and more nutrients in a DWC system, you’ll have to worry about your waste water management more.

• Disease and yield are fairly equal across systems and good maintenance makes a bigger difference on how much yield you can extract from your hydroponic set up.

• DWC is the most forgiving system for new growers and considered the most accessible technology when compared to NFT and ebb and flow systems.

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A DWC system offers more reliability and temperature stability because roots are always submerged in water.

Fun fact: Growcer’s first farms were NFT systems but we’ve since switched to DWC because it’s more reliable and forgiving for new growers.

What is Deep Water Culture (DWC)?

In a deep water culture (DWC) system, plants sit on floating rafts under lights with their roots in nutrient solution.

A DWC system can be passive (run to waste) or active (recirculating). Growcer’s Osiris farm is an active system where nutrient solution is recirculated throughout. This is a more sustainable approach instead of wasting perfectly fine nutrient solution, but requires more cleaning and filtering from the operator.

What is Nutrient Film Technique (NFT)?

In a nutrient film technique (NFT) system, plants sit in gutters with a shallow nutrient solution that flows by plant roots.

An easy way to picture the difference between DWC and NFT is to imagine plants sitting in a lake (DWC) or a river (NFT).

Fun fact: When Growcer first started we built a NFT system. In early 2020, we switched to a DWC system because we found deep water culture was more forgiving for new growers and this aligned with our mission to make farming year-round accessible to all. When it comes to accessibility and ease of use, DWC wins the battle.

Benefits of Deep Water Culture Hydroponics vs. NFT

Reliability

What happens if you lose power? Will your plants survive?

In a DWC system, roots are always sitting in nutrient solution. So even if the power goes out, your system will be stable for a few days because the plants still have access to their food.

In a NFT system, because roots are in a film of nutrient solution that is pumped under the plants, as soon as the pumps go out (or get clogged), you could lose all your plants.

This is of course dependent on the plant load and age at the time - hydroponics is not a zero-sum game. You can still revive your plants in a NFT system if you get the power back on within a reasonable timeframe. Plants are more resilient than we think.

Ultimately, the reliability of your hydroponic system determines how frequently you can harvest and pay off your investment. If you’re losing harvests left, right and center, your ROI will extend beyond what you anticipated.

Temperature and nutrient stability

Plant processes such as photosynthesis (creating food/energy), transpiration (water loss), respiration (breathing), seed germination and flowering (bolting) are all influenced by temperature.

By controlling temperature, indoor plants can outperform their outdoor counterparts and grow bigger, faster.

A DWC system has better temperature stability and the water’s temperature stays closer to what roots need. The bigger body of water is not affected by ambient temperatures as much as a smaller body of water, like with a NFT set up.

In a NFT set up, the shallow nutrient film has low volume and high surface area so it will heat up quickly to ambient temperatures.

You would also have to consider the potential of an uneven distribution of nutrients along the troughs. Because it is a thin layer of nutrients, nutrients can get depleted along the gutter, especially if older, hungrier plants are present.

“Because it is a thin layer of nutrients, nutrients can get depleted along the gutter, especially if older, hungrier plants are present. ”

And when plants at the end of your troughs don’t get enough nutrients, they don’t grow as fast or as big so you’re left with uneven plant sizes within your farm. This is not a problem if you enjoy explaining to customers why your product is so variable from week to week.

Water is a good buffer for plant health and the more water you can have per plant the better.