Kratky vs DWC – What’s the difference – Aeration vs No Aeration
This Video is from the Youtube channel: “Growing Answers”.
Deep Water Culture (DWC) and the Kratky method are both hydroponic systems used to grow plants without soil. However, they differ in their design and operation:
- Deep Water Culture (DWC):
- In DWC, plants are placed in a net pot or container where their roots hang in a nutrient solution.
- An air pump is used to oxygenate the nutrient solution, providing oxygen directly to the roots.
- The roots are submerged in the nutrient solution, which needs to be monitored and maintained at a proper level.
- As the plants grow, the nutrient solution needs to be topped up and the pH and nutrient levels should be regularly adjusted.
- DWC systems usually require more equipment, including air pumps and airstones to maintain proper oxygenation.
- Kratky Method:
- The Kratky method is a passive hydroponic system that does not use air pumps or additional equipment for oxygenation.
- Initially, plants are placed in a container with a nutrient solution. Unlike DWC, the nutrient solution is not replenished as the plants grow.
- The container is designed in a way that the roots are partially submerged in the nutrient solution, and as the plants consume the solution, an air gap forms between the roots and the solution.
- Over time, the air space grows as the nutrient solution is used by the plants, allowing for oxygen to reach the roots.
- The nutrient solution in a Kratky system is not actively aerated; instead, it relies on a balance between the initial solution and the air space that develops over time.
Key Differences:
- Aeration: DWC actively oxygenates the nutrient solution with the help of air pumps, while the Kratky method relies on the development of an air gap between the solution and the roots as the plants consume the nutrients.
- Maintenance: DWC systems require more monitoring and maintenance, including adjusting nutrient levels and pH and topping up the solution. Kratky systems are low maintenance once set up, as they rely on the initial nutrient solution without replenishment.
- Equipment: DWC typically requires additional equipment like air pumps and airstones, while the Kratky method is a simpler and more passive system.
Both methods have their advantages and drawbacks, and the choice between DWC and the Kratky method often depends on factors like the type of plants being grown, space available, and the level of involvement or maintenance desired by the grower.
White LED VS RED/BLUE/WHITE LED Grow Test Ep.1 2018
In this video I grow basil hydroponically to gather data on whether or not aerating water has significant benefits. What is happening when you aerate water?
I’d have thought oxygenating the water would’ve had a more noticeable effect. Although in a shallow tub the 02 doesn’t have long to diffuse bubbling to the surface. Looking forward to seeing how it goes with the clones in pt 2
Russell Raccoon that could be true. Thanks for the comment
Hello. is that relevant? my understanding from running an aquarium is that bubbles bursting on the surface of the water is what causes oxygen. it is the movement of the water surface. this is why the shape of a fish tank can make a difference. so if you have 2 fish tanks, both 50 gallon but one is tall and the other short and wide… the shorter one could house more fish. due to a larger surface area, which can allow for more air in to the water… but don’t trust me, this is just what I read on the internet whilst doing research into fish care.
the bubbles going up doesn’t add the air. but it does stir the water around so it doesn’t go stale or something… but smallest bubbles are better, because millions of tiny bubbles breaks up the surface way more than a few large bubbles. problem with a larger surface area is of course larger footprint required
Question; If you put a stone tip at the end of the tube (like you use in fish tanks) would that help with the diffusing of the O2?
Nice video with detailed information, thx for sharing your experience. I hope your next part will be more conclusive.
Good luck.
I’ve been playing with DWC Basil for about two years now and i’ve found that an aquarium filter like the “Eheim Aquaball” work well enough for aerating the water. Also when i close the Cabinet i can even sleep next to it.
I think Basil might not need that much oxygen especially compared to Tomatoes or other fruiting crops.
Also i’ve found that when i use fresh cuttings they seem to produce best on the second to about fourth or fifth Harvest.
After that they either get some kind of Mold (usually my fault) or just seem to take longer and longer to bounce back.
Also the taste/smell changes as the plants get older.
Does any of that fit your observations?
btw: What pH and ppm values do you use? A pH of 6-8 and PPMs of ~700-1200 work pretty well for me.
Do you adjust the pH only once or do you let it sit for a night to check again (i never do because im lazy but its highly recommended by most non-lazy hydro growers).
I had not thought about using a fruiting plant. I wanted to use basil cuz I could taste it. I wont eat tomatoes. But I did use tomatoes in the other videos and had great results. Not to mention fast growth. I do not let the water sit when I PH. I have done it so many times that I have it down to a science and know what it will be after it sits. Its usually Ph to 6.5. I know it should be higher to start for hydro though. PPM for the aggressive veg nuts solution was 1400. Last hydro grow I noticed some mold on the tomato plants. I believe that air circulation needs to be much stronger with hydro to prevent mold. also pruning the lower parts helps.
I also left the ph alone once I put it in the bins. I didnt want to alter anything so that I could better log what happens to the properties of the water.
Same here for pH-adjusting: I measured how much in need once and it usually works out well.
I think pH 6,5 is right for hydro-basil, i found 5,5-6,5 somewhere and been running 7-8 for a while without major problems.
The mold starts usually at the base of the stem when the plants get really old and woody and the weather gets warm and more humid. In Winter everything works fine usually.
I could put a fan in but i think basil doesn’t really like wind or any other kind of weather.
I don’t think its a problem though because the younger plants seem to grow more aggressive anyways and it gives me an excuse to try new systems (“the plants are dead anyways, lets try a bed of Hydrocorrels with constant flow now”). Also the roots get quite massive over time and i suspect that the ones inside of the tangled mess don’t get much nutrients or oxygen.
In a perfect world i would have another box just for starting cuttings and getting them bigger so i could start new plants for every seconds harvest or so.
Thanks! Great to see somebody testing both methods in a (more or less) scientific method.
Thanks for doing these experiments and videos! I really appreciate how honest and rigorous you are compared to other people on YouTube and on the internet. For example, you show us your inconclusive result and talk about the small sample size.
YouTube videos where people compare growing methods with a sample size of 1 are my pet peeve. I really appreciate your work.
Thank you for being clear with your methodology. Very useful to repeat your experiment. Glad you realized sample size prevents a clear conclusion. Great explanations to what’s going on with the water nutrients.
You need to pick one plant and clone it, so that all of them are the same, then start the experiment with all the exact same plant, then you won’t need to grow 50 plants and average your results, you will get a better result I think? Cool video!
Magic Smoke FPV I did clone it. that was in the following video. I always do it both ways to see if results vary.
Thanks Man, your’re an inspiration! Keep it up. You have advanced my knowledge immensely . I appreciate your experiments, and in-depth information. You are doing a true scholastic education, which is so needed, but not being stated by others.
This is a great video. Thank you for taking the time to do this. I will be watching part 2 tomorrow. Love your subject matter and your approach.
I’m liking your videos and the approach you take. It’s also nice to see someone who appears to understand that “science” (the scientific method) is a method, not an entity, not a person, and not an authority or celebrity in a white coat. Haha.
Respect. And thanks for taking the time to do what you’re doing and to share it for everyone’s benefit.
Peace.
Do you have a video experiment of grow quality when doing water changes vs. not doing water changes and just topping off with nutrient solution? I’d like to see a video done with either DWC or Kratky. I know some people do not do water changes and all they do is check TDS and Ph, they just check their TDS levels and add accordingly. I’ve always wondered how this effects growth and overall health of plants. I’ve always done complete water changes with new nutrient solutions myself using DWC.
HD Bagger not a dedicated one, but I’ll consider it. https://youtu.be/6xG7U5OWs2Q
I really love your way of methodically testing and thoroughly explaining these phenomena and I really enjoy your videos. Keep it up 🙂
agreed
Hi love your videos seriously.Really helpful ! And i wish to ask, if i use the liquid fertilizer, do I still need potassium, calcium nitrate etc? Because I saw you add something else beside the fertilizer in some other video. Thanks alot once again for such wonderful videos
If you use liquid fertilizer that’s meant for hydro, you should not have to add anything. Some plants may benefit from additional Nitrogen or calcium though.
Great video. I appreciate your science outlook. You seem to contradict yourself about aeration, PH, and PH “stabilization” vs “PH creep” which is what most need to deal with as the water sits in a container with roots in it… AS water evaporates, it will climb in PH faster, yes? And thus the water looks more contaminated, higher salts, and we need to change out the water more often, yes? And, we need to check the PH more often, as many plants crave acids, and are not happy in hydro over 6.5, THUS, we are constantly fighting PH creeping up and up over time as water evaporates, and is a major issue on how often water needs to be changed out.
When I grew with DWC, I found that one problem with the standard method is that the airstones used for aeration get clogged with salts from the added nutrients and their output is reduced. To address that problem, rather than using an air pump and an airstone, I used an aquarium power head that had an aeration function. The way that works is a short length of clear tubing – like you would use with an air pump – is inserted into the output nozzle of the power head with the other end above the water line. Then, when the pump is running, the flow of water past that tubing creates a vacuum that pulls air into the stream and mixes it with the water – thereby, aerating it. This method is far more consistent over time and requires no replacement of airstones, or monitoring their condition. The power head also produces much better circulation of the nutrient solution across the roots. Making this change made a noticeable improvement in the performance of the system overall.
Of course, I no longer grow using the DWC method. I now use an ebb and flow/flood and drain system. The roots are flooded with nutrient solution for 15 minutes every hour and then their containers are allowed to drain completely back into the nutrient reservoir which exposes the entire root structure to air, while leaving them wet with nutrient solution.. This process aerates both the roots and the nutrient solution. The roots get aerated during the drain portion of the cycles. And, the nutrient solution gets aerated during the flood portion of the cycles – through the movement of the nutrient solution through the containers and draining back into the reservoir. The action of the nutrient solution falling back into the reservoir causes splashing and disturbance of the surface, which aerates the solution.
why does it matter if the nutrient solution is being aerated in your ebb/flow system? the roots are getting oxygen directly from the air
@Jake Keys It matters to prevent the rise of anaerobic bacteria. The aerobic bacteria are helpful, but not the anaerobic bacteria.
@Richard Owens thanks for the explanation, I didn’t know that
@Richard Owens
Richard, The Kratky method seems to work well, too, but there must be a rise of anaerobic bacteria in those jars/buckets. Yet the plants seem healthy. What difference do you see?
i used to grow in passive wick system, then i tried aerating it, it seems like the aerated crops grew a week faster than before. i said wick system but its similar to kratky since in the end the roots are drinking straight from the nutrient anyway. i use those long black rubbery flexible pipe as air stone, im sure there are other factors but a week faster is fascinating to me.
Do you change water levels in DWC as root grow to bottom of the bucket ?
Or just change out water at same level?
Great video explaining DWC and krack !! 🌱👍
real DWC you leave the roots submersed. aerated kratky is just kratky with bubbles and you let the water level drop.
When you aerate – process wise you *must* balance pH *after* either the water has reached max oxygenation or the supply of aeration is at maximum effect. Stops any ‘overnight’ pH drifts due to oxygenation.
As for alkalinity – you should be exhausting those buffers prepping the water in the first place. Just like using something stable and preferably strong to alter pH – yes strong – weak acids have a far more reversible action (lemon juice, some vinegars, phosphoric acid).
Do the above *correctly* and all you have affecting pH from the hydro is plant feeding and actual evaporation – the aeration affects nothing, you should be at max oxygenation.
The larger the volume of water in your reservoir – the slower your pH will drift when all is right and well.
That’s how you concisely cover pH and aeration in relation to water for hydroponics.
Doesn’t even touch on how photosynthesis cycles and heat changes create changes in pH, but I digress, this is about pH and aeration.
Great video I love it. Quality information and great explanation. I’ll suscribe. I just have a question how many time did you leave the air pump on ?
Used to aerate my hydroponic basil… it does increase yields (~15 – 20%) but by proper pruning of my basil plants (harvesting once or twice a week) I’ve been getting more basil than I can use without the extra hassel (e.g. topping off water volume) of aeration. At the end of the season there’s a huge harvest for flash freezing… and for lots of cuttings for the (much smaller) indoor winter basil crop.
Thanks GA. Your insights and methods are appreciated.