DWC vs NFT vs Kratky: Choosing the Right Hydroponic System

Three systems dominate home hydroponic growing: Deep Water Culture (DWC), Nutrient Film Technique (NFT), and the pump-free Kratky method. Each suits a different type of grower. This guide explains all three precisely so you can choose confidently.

Deep Water Culture (DWC)

How it works

Plant roots hang through net pots into a reservoir of nutrient solution. An air pump drives one or more air stones that continuously oxygenate the water. The roots are submerged in the solution and receive constant moisture, nutrients, and dissolved oxygen simultaneously.

What you need to build it

Storage tote or dedicated reservoir (1–5 gallons per plant)
Net pot lid or individual bucket lids with net pot holes
Air pump (1 watt per gallon is a reasonable rule of thumb)
Air stone and airline tubing
Nutrient solution + pH/EC meter
Net pots and growing media (hydroton/clay pebbles or rockwool)

A single-plant 5-gallon DWC bucket can be built for $25–$50 in components.

Strengths

Forgiving: if your air pump fails, roots have hours of buffered oxygen in the reservoir
Excellent root development - large, unconstrained root mass
Fast growth due to constant nutrient contact and high dissolved oxygen
Easy to observe roots and spot early problems
Scales easily (add more buckets)

Weaknesses

Reservoir needs changing every 1–2 weeks (old solution accumulates microbial load)
Water temperature management is critical - above 72°F, dissolved oxygen drops and Pythium risk rises
Higher water volume than NFT for equivalent plant count

Best crops

Lettuce, basil, mint, spinach, bok choy, cherry tomatoes (with adequate lighting), cannabis.

Nutrient Film Technique (NFT)

How it works

Plants sit in net pots positioned in the top of slightly sloped channels (1–4° angle). A pump delivers a continuous thin stream of nutrient solution from a reservoir at the high end; it flows along the channel bottom, passes over root tips, and drains back to the reservoir. The upper root mass sits in humid air; only the root tips touch the film.

What you need to build it

NFT channels (PVC guttering, purpose-built channels, or repurposed materials)
Reservoir and submersible pump
Timer (some systems run continuously; others cycle)
Channel supports to create the slope
Net pots
Nutrient solution + meters

A 12-site NFT system with channels and pump runs $60–$150 to build from components.

Strengths

Water-efficient: 10–30% less water per kg of yield than DWC
High root oxygen exposure - roots mostly hang in air, not submerged
Scales well for continuous production (plant young seedlings at one end, harvest mature plants at the other)
Commercial standard for leafy green production worldwide

Weaknesses

Pump failure is immediately dangerous: roots dry out in 30–60 minutes
Slope must be precise - too flat = stagnant water; too steep = roots dry out before absorbing nutrients
Channels require cleaning between crops
Less forgiving for beginners than DWC

Best crops

Lettuce (the canonical NFT crop), herbs, spinach, bok choy, kale. Poor choice for fruiting plants with large root systems.

Kratky Method (Passive Hydroponics)

How it works

The Kratky method is deceptively simple. Plants sit in net pots above a sealed reservoir filled with nutrient solution. The key design element: a deliberate air gap is maintained between the waterline and the bottom of the net pot. As plants consume water, the solution level drops - the air gap grows, exposing more root mass to oxygen while the root tips remain in solution. No pump, no timer, no electricity required for the water system.

What you need

Any opaque container (mason jar, storage tote, bucket)
Net pot lid or individual hole per plant
Nutrient solution - mixed once, not recirculated
Optionally: pH/EC meter (less critical since solution isn't refreshed continuously)

Cost to start: $5–$20. The lowest-barrier hydroponic method that exists.

Strengths

Zero electricity for the hydroponic system (lighting still required)
Silent - no pumps
Near-zero maintenance between setup and harvest
Excellent for herbs and lettuce at small scale
Ideal for off-grid, travel-period, or backup growing

Weaknesses

Nutrient solution is not refreshed - waste products accumulate, salt concentration increases at root surface over time
Less control: can't easily adjust EC or pH mid-grow without disturbing the system
Not suitable for large plants or long grow cycles (more than 8–10 weeks)
Temperature management still matters - warm static water is more vulnerable to Pythium than aerated DWC

Best crops

Lettuce (6–8 week cycle is ideal), herbs (basil, chives, mint), spinach. Use Kratky for single harvests, not continuous production.

Side-by-side comparison

| Factor | DWC | NFT | Kratky | |---|---|---|---| | Pump required | Yes | Yes | No | | Electricity use | Low | Low | Minimal (light only) | | Build cost | $25–$80 | $60–$150 | $5–$20 | | Maintenance | Medium | Medium | Very low | | Pump failure risk | Low | High | None | | Water efficiency | Medium | High | High (no recirculation) | | Beginner-friendliness | High | Medium | Very High (passive) | | Best for scale | Yes | Yes | No (small scale only) | | Best for continuous harvest | Yes | Yes | No (batch only) |

Which system should you start with?

New to hydroponics, want to learn the fundamentals: DWC in a 5-gallon bucket. Lowest failure risk, teaches you pH/EC management, excellent results with herbs and lettuce.

Want zero complexity, minimal time commitment: Kratky in a dark mason jar or tote. Ideal for one to four plants, one herb or lettuce crop at a time.

Want to scale to 12+ plants and grow year-round: NFT. The learning curve is steeper but it's more water-efficient and purpose-built for continuous production.

This guide is reviewed against published horticultural research. It is not a substitute for advice from a certified horticulturalist.