DWC Vs Kratky Hydroponic For Growing Lettuce

PSPSMITH says:

Note to those calling this experiment “bad science”:

It’s not automatically bad science, per se. Could the experiment be improved? Obviously, as is implied several times throughout the video. The results simply show that in this single, 1 to 1 comparison trial, DWC mod versus Kratky, in a relatively cold room, provided similar nutrients and light levels (and visually similar sprouts), the outcome was that the plant growing in the Kratky method performed better. While it’s obvious that this was an extremely small test group, I believe this experiment still has considerable merit.

Yes, it could be argued that the cold ambient temperatures caused the DWC plant roots to remain at a relatively cooler temperature than its Kratky counterpart, due to the circulation of ambient air created by the air pump and stone. Personally, this is my suspicion. However, this may simply show a possible strength of Kratky method versus DWC in cooler temperatures when growing short cycle, leafy greens. To be sure this is the case, one would need to do another test that included tracking nutrient solution temperatures throughout the experiment and comparing the results based on ambient temperature and method utilized. The experiment could also be replicated in a warmer environment, to see if temperature was the critical/limiting factor.

Additionally, it is also possible that this modified DWC method behaves differently enough from true DWC that the results may not accurately represent outcomes using traditional DWC methodologies. In most DWC I’ve seen and used, DWC required roots always completely submerged and nutrient solution aerated. This is typically achieved through floating raft systems or DWC “bucket” systems utilizing float valves and additional solution reservoirs to keep the nutrient solution completely topped off at all times. If someone wanted, they could perform this type of experiment with those changes. I’d be interested to see if the results would be any different.

In the end, there is no point in attributing emotions to small sample experiments such as this. It’s clear that this in not a completely comprehensive, long-term, exhaustive study of the two methods (stated several times throughout the video.) DWC does not need our appreciation, nor does the Kratky method. There is also no prize (real or imagined) in championing one method over another as being objectively superior in all situations. Having been directly involved in hydroponic and aquaponic systems for years, I can personally state that both methods (DWC and Kratky) have their strengths and weaknesses, from both a production and financing perspective. In my experience, Kratky is often superior to DWC when it comes to small scale, short life, fast growth, leafy greens and herbs (leaf lettuces, basil, etc.) Why pay to buy the pumps/tubing/airstones/float valves/reservoir tank/floating rafts/etc and use additional electricity to aerate nutrient solution if growing two or three small heads of lettuce is the goal, and there is enough dissolved oxygen or oxygen available to the roots suspended in the air gap to grow in an extremely healthy fashion using the Kratky method? Kratky is simple and very approachable for this type of usage. Kratky does, however, often encounter considerable trouble when trying to grow larger, longer-life plants such as peppers and tomatoes, as the growing solution often needs refilling , and oxygenation via air pump is generally necessary (no longer Kratky at that point.) This is where DWC really shines, as this method excels at growing these types of long-life plants that need a constant supply of nutrient solution and considerable amounts of dissolved oxygen to grow well over long periods of time. For these applications, DWC is almost always superior.

In my opinion, although this experiment was not extensively comprehensive and the test group was small, it is still quite good science. For the practical purposes of a person getting started in hydroponics by simply growing a single head of lettuce under a grow light, I think this is a valuable guide that demonstrates the strengths and simplicity of the Kratky method of hydroponics.

Psycho Rooks says:

Late response, but my immediate observation is that the turbulence caused by aeration is hindering root development. This may be less of a concern with a weaker flow or wider basin. As always, great video, thanks again!