We love growing plants indoors with our hydroponic systems, and designing your own DIY versions is a blast.
But air pumps are recommended for optimal health and growth, and let’s face it; these are harder to come by.
Is it possible to use hydroponics without an air pump?
Using hydroponics without an air pump is possible, though it usually requires more work checking the water levels and cleaning out the container to prevent bacteria. The Kratky method of keeping an air gap between the top and bottom of the roots is the easiest to set up and use without an air pump.
Look ahead for more details on this system, why you need an air pump and ways to go about keeping your plants healthy.
Table of Contents
Why Use An Air Pump With Hydroponics?
Before we look at making hydroponics without an air pump feasible, we need to understand why it’s so important in the process.
Once we better understand this, we’ll be able to adjust our system to make up the difference.
Oxygenation
The biggest reason for an air pump is to oxygenate the water.
As your water solution goes through the plants’ roots, the plants will pull the nutrients AND oxygen out of the water.
Whatever water you have left has less oxygenation over time.
Without an air pump, the water will get stale, as it were, and provide less oxygen to the plants.
Movement For Mold And Algae Prevention
Hydroponic reservoirs are warm and full of extra nutrition. Plants love this, but so do other forms of life like mold, algae, and other bacteria.
If you leave your water alone, these will grow in the tank, steal the nutrients, or infect the plants.
Movement, such as a flowing stream, prevents pockets of algae and mold from building.
Air pumps provide a constant bubbling motion that’s just enough to prevent quick buildup and make it, so you don’t have to clean your system all the time.
Better Water Balance
Both movement and oxygen help to keep the water chemicals in better balance. One of the most important elements is the pH level.
An air pump will play a small, but no less present, role in keeping the level stable.
Hydroponic systems should keep their water solution somewhere between 6-7.
How To Use The Kratky Method With Hydroponics
All of the above is critical for keeping healthy hydroponic plants, but there are workarounds.
One of the most common methods without an air pump is called the Kratky Method.
In this section, we’ll give you the basics, so you know how to check it out and see if it’s a good fit for you.
What Is The Kratky Method?
This method is similar to hydroponics in that the plants’ roots dangle into a special water system to retrieve their nutrients and require no soil to grow.
Kratky requires no additional nutrients, so whatever you’ve been using for the normal hydroponic solution will be fine.
As with other hydroponics, you place a seedling in a net pot with a medium such as pebbles, clay rocks, or Rockwool.
The plant uses the nutrient solution and oxygen from the water to grow while taking sunlight or a special grow light.
In the Kratky method, the roots are left to dangle in the water all the time. As the water goes down, a gap is left between most of the roots and the water.
The air here directly helps oxygenate the plant and solves the oxygen issue.
Plants will actually develop something called “air roots,” which let them pull the oxygen right out of the air.
The roots will also stretch further down, making them longer than normal to get the water.
This process will continue for the rest of the plant’s life.
To help with the chemical balance and mold prevention, you’ll need to change and refill the water every few days, depending on how quickly the plant drinks the water.
You may also need to wipe down the bucket/container more often.
How To Set Up A Kratky Hydroponic System
Setting this is up is super easy.
Here is a quick rundown of the steps:
- Fill your hydroponic reservoir with distilled water (or tap water with the chlorine removed using a cut-up lemon and 24 hours).
- Add your nutrients and fertilizer as recommended by your specific product.
- Check the pH level to make sure it’s between 6-7.
- Add your seed pod and growing media to the container (net pots are an easy DIY option).
- Poke holes in the lid if needed to ensure airflow.
- Let grow.
- Check chemical levels daily and alter as needed.
- Ensure at least the bottom 1/4″ inches of roots are touching the water.
- Clean and replace the water every 3-5 days or when the water is half gone from your last refill.
- Harvest the plant when it’s grown.
Video Of The Kratky Method Setup
What Can You Grow With The Kratky Hydroponics Method?
Kratky’s method works with any plant, just like most hydroponic systems, but there are some where it’s easier and much more successful.
Here are a few we recommend:
- Lettuce
- Spinach
- Cilantro
- Parsley
- Cabbage
- Cherry Tomatoes
- Rosemary
- Basil
- Catnip
- Chives
- Mint
- Beans
Lettuce is the easiest and a great starter plant in general for hydroponics.
It only takes 6-7 weeks for it to grow and harvest.
Any other plant will work, but it requires a much bigger container, more water, and a lot more checking, cleaning, and work on your part.
Of course, you can save yourself a bunch of time and work by simply buying an AeroGarden and getting everything set in one go.
Check out our reviews of the best AeroGarden for lettuce and small herbs.
Tips For Hydroponics Without An Air Pump
When skipping an air pump, there are some special tips and tricks you’ll want to keep in mind.
Mosquitos
Exposing the standing water to the air may attract mosquitos.
If you keep your hydroponic plants inside, this won’t be a big deal.
But if you keep some outside, it’ll draw mosquitos quickly.
They like humid air and wet, warm places. The air gap between the water and the top of the container for your plant is perfect for them.
Keep mosquito traps nearby, or don’t keep your plants outside in warmer weather.
Uneven Water Level
If you use a wide container or it’s on an uneven surface, be aware of how much your water reaches the roots of all your plants.
I made the mistake of using a row of roots and not realizing the deck my plants were on was slightly tilted.
The plants on the low end could reach the water, but the high end was just out of reach.
Guess which ones died quickly? Don’t make this same simple mistake.
pH And Electrical Conductivity In Your Nutrient Solution
Check your pH levels daily. It should be between 6-7.
Adjust the water as needed to keep it here.
Also, check your EC or electrical conductivity levels often.
As the water gets used, the levels change drastically based on the amount of salt in the water. When it’s off, the roots will get “clogged” and stop absorbing any nutrients.
The EC should be between 1.2 and 2.0.
Fresh water and more water can set the levels back to the right again.
Clean More Often
Cleaning the container and replacing the water often will help prevent mold and algae.
To be safe, change it out and wipe it down at least every 2 weeks, though one week would be best.
Another big concern is to use safe plastic as your container. Some will leak chemicals that can poison your plant or even you later on.
Check out our guide to safe plastics for hydroponics by clicking here.
Watch The Air Gap
When you check your water daily, always be aware of the air gap.
You want some air between the plant’s body and the water. This is a must without an air pump because it won’t get the oxygen it needs otherwise.
However, you don’t want the gap, so large your roots barely touch the water.
Other Hydroponic Methods For Use Without Air Pumps
The Kratky method is one of the most effective, but it’s not the only one. Here’s a quick list of other ones to try:
Aeroponics – This method keeps the roots suspended in the air all the time.
It requires special sprayers that go off on a timer.
It’s advanced and tough to set up, but it requires no air pump.
You may also want to check out our comparison of Aeroponics vs. Hydroponics vs. Aquaponics.
Ebb and Flow – Ebb and Flow fill up the growth area with roots and let it drain back into the hydroponic reservoir.
During the time the water is down, the air gets into the roots.
But while it doesn’t need an air pump, it still works best with one.
Wicks – Wicks pull the water through a nylon wick into the growing medium. The roots are partially exposed to the air most of the time.
This method is cool but a little tricky; it’s not for newbies and requires some experimentation.
Nutrient Film Technique – This is a popular commercial method that has plants lined up in rows over “gutters” as the water flows through in a circle.
Capillary mats pull the water into the roots.
The flowing process adds air and motion, but it requires a serious water pump and a crazy cool but involved setup.
This is overkill for most at-home gardeners.
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