Kratky vs DWC: Which Hydroponic Kit Fits You?

Kratky vs DWC is one of the first choices a new hydroponic grower faces, and the two are easy to confuse. Both hang plant roots in nutrient solution. The difference is how those roots get oxygen, and that one difference changes almost everything about how the kit is run.

The short answer

A Kratky kit is passive: no pump, no power, and the water level is allowed to fall so the upper roots can breathe in the air gap. A deep water culture (DWC) kit uses an air pump and air stone to bubble oxygen into the solution, so the roots can stay fully submerged and the level is kept topped up. Kratky is simpler. DWC can support bigger, faster plants.

How each one oxygenates the roots

Roots need oxygen to take up water and nutrients. In the Kratky method, the plant drinks the solution down over time. The space that opens up between the lid and the water fills with humid air, and roots in that space take in oxygen directly. The article on the Kratky air gap explains why this is so important.

In DWC, an aquarium-style air pump pushes air through a stone at the bottom of the reservoir. The bubbles keep oxygen dissolved in the water, so the roots can sit in solution all the time. Growers top the reservoir up and often replace the solution on a schedule.

Side-by-side comparison

• Power: Kratky needs none. DWC needs a pump running around the clock.
• Noise: Kratky is silent. DWC pumps hum, which matters in a kitchen or bedroom.
• Upkeep: Kratky is set and largely left alone. DWC solution is topped up and usually changed periodically.
• Failure risk: Kratky has no moving parts. In DWC, if the pump stops, submerged roots can run short of oxygen quickly.
• Plant size: Kratky suits leafy greens and herbs best. DWC handles large, thirsty plants more easily.
• Growth speed: Well-run DWC is often faster, because roots are constantly in oxygenated solution.
• Cost to start: Kratky is cheaper. DWC adds a pump, tubing, air stone and check valve.

When a Kratky kit is the better choice

• You want lettuce, herbs or other greens on a counter or windowsill.
• You want something quiet that does not need an outlet.
• You are new to hydroponics and want as few things to manage as possible.
• You may be away for a week or two during a short crop.

When a DWC kit makes more sense

• You want to grow large fruiting plants such as tomatoes or peppers through a long season.
• You are willing to manage the solution more actively.
• You want to push growth rate and do not mind the hum of a pump.

Watch out for mislabeled kits

Some kits marketed to beginners include an air pump and are really DWC, even if the listing mentions Kratky. If a kit includes an air pump, air stone or tubing, it is designed to be run as DWC, with the level kept up. Running it as Kratky without the pump, while also keeping the level high, removes the oxygen supply from both methods. The guide on how to choose a Kratky kit lists what to check.

Can you convert one to the other?

A DWC reservoir can be run as a Kratky system: leave the pump out and let the level fall from the bottom of the net pots, as in Kratky kit setup. A Kratky container can become DWC by adding an air pump and stone. What you cannot do is mix the rules: a full reservoir with no aeration is the setup most likely to cause root rot.

Countertop gardens with a pump and built-in light are another powered option; the post on Kratky kit vs AeroGarden compares them.

Bottom line

For most people starting out with herbs and greens, a passive Kratky hydroponics kit is the simpler, quieter and cheaper option. DWC earns its extra effort when the plants are big and the season is long.

Frequently asked questions