Dear plant lovers and friends of healthy breathing air,
In recent weeks, there have been repeated questions about this, so today we are addressing one of the most important elements in our AIRY system: the water tank.
A well-maintained water tank is the key to success for healthy and happy plants. Here are some tips and tricks to get the best out of your AIRY system:
1. Water quality: Always use clean, preferably low-lime water for your AIRY system. This helps reduce deposits in the tank and ensures the well-being of your plants. The good thing: plants like "stale" water. This is ensured by the water tank in the AIRY biofilter without any further effort on your part.
2. Water level indicator: Before we invented AIRY many years ago, water level indicators only existed for the so-called "hydroponics." Plants in hydroponics literally stand in water in a dead, inorganic environment. This must always be kept in the "optimal" state for the system to work. With AIRY, it's different. There is a "minimum" and a "maximum" that signals the fill level to you in a simple and, as we think, very beautiful way.
3. Fill level: You can always refill the water tank in the AIRY system up to the "Maximum." BUT: There are plants, such as the snake plant, that sometimes prefer and need it a bit drier in between. Therefore, please consider the basic requirements of the plant you are using. You can also find hints and tips here on the blog, via our chatbot, or contact us directly (info@airy.green).
4. Use of water additives: Depending on need and plant type, you can occasionally add special additives like fertilizer or our AIRY Vitalizer to the water in the tank. However, be sure to follow the dosing instructions to avoid, for example, over-fertilization. The basic rule is: less is more!
5. How often to refill: In our advertising and also on our website, we say that the water tank of an AIRY lasts for quite a long time (several weeks). That is true. However, in the first weeks, it often needs to be refilled much more frequently. The reason is that the relative humidity in the surrounding air is too low. The plant and water tank then release MORE moisture into the room air until it stabilizes at a comfortable level for the plant (40 to 60%).
6. Substrate or filling neck: There is a simple rule for watering derived from experience over the past years:
After planting the AIRY system, please water carefully over the substrate NEXT TO the plant during the first four weeks.
After that, just pour directly into the water tank via the filling neck. The only exception: If the AIRY system is completely dried out, please pour some water over the substrate again before filling the water tank. Only then is the capillarity of the mineral substrate restored (always nice to hear the crackling the substrate makes when it absorbs the water).
Finally, a word about the size of the water tank in the AIRY Biofilters, as it varies:
- AIRY S: about 0.8 liters
- AIRY M: about 1.6 liters
- AIRY L: about 3.2 liters
Oh yes, one more point:
The water level indicator, that long rod with the small blue cloud at the tip, is lifted by one or two air-filled balls. So please don't be surprised if you pour water into the tank and at first NOTHING happens. This is especially the case with the AIRY Biofilter L and also makes sense: The water must cover the bottom of the tank and fill it enough for the balls to rise. And that takes a moment given the size...
If you have any questions, feel free to contact us anytime (info@airy.green).

The author: Elisabeth Böttcher
Elisabeth is the managing director of AIRY and is responsible, among other things, for customer support. She has over ten years of experience with plants growing in the AIRY biofilter and gladly shares her knowledge as an expert along with tips and tricks. She focuses on healthy indoor air, effective plant care, and everything that contributes to a natural, beautiful home.
2 comments
Peer-Arne Böttcher
Dear John,
Please excuse the very late reply to your comment. We just came across it by chance and realized that we are not automatically informed about the comments on our own blog…
To your points:
- the foul odor will probably have been caused by a lot of dirt accumulating in the water tank. This is encouraged, for example, if water is mainly poured over the mineral substrate or if fertilizers get stuck in the tank. In this respect, your cleaning measure was absolutely correct – and obviously successful, at least in this respect!
- to your second point. These are very likely to be fungus gnats. Although they are completely harmless to us humans, they are totally annoying and can also harm the plant in the long term. They are becoming increasingly common as plants are grown in greenhouses without peat and are therefore (more) biologically sound. Good for the environment, but also good for the reproduction of fungus gnats. The measures to be recommended are twofold: please collect the already living insects with so-called yellow boards, while the larvae can be controlled with various biologically sound means. We have had very good experience with the products from “Plantura”.
Please contact us directly (info@airy.green) if we can help you further or if you have any other questions.
Dear John,
Please excuse the very late reply to your comment. We just came across it by chance and realized that we are not automatically informed about the comments on our own blog…
To your points:
- the foul odor will probably have been caused by a lot of dirt accumulating in the water tank. This is encouraged, for example, if water is mainly poured over the mineral substrate or if fertilizers get stuck in the tank. In this respect, your cleaning measure was absolutely correct – and obviously successful, at least in this respect!
- to your second point. These are very likely to be fungus gnats. Although they are completely harmless to us humans, they are totally annoying and can also harm the plant in the long term. They are becoming increasingly common as plants are grown in greenhouses without peat and are therefore (more) biologically sound. Good for the environment, but also good for the reproduction of fungus gnats. The measures to be recommended are twofold: please collect the already living insects with so-called yellow boards, while the larvae can be controlled with various biologically sound means. We have had very good experience with the products from “Plantura”.
Please contact us directly (info@airy.green) if we can help you further or if you have any other questions.
John Calaway
Dear Airy,
I have the large two-plant Airy, and the round single plant Airy. The water is both reservoirs smell quite foul. Our watering practice is to allow the meter to drop to the bottom reading before refilling. The plants seem to be healthy and thriving—cream anthurium.
With some flexible tubing I siphoned the water in the larger planter, flushed the substrate, refilled the reservoir to capacity, and drained it again. The foul smell is gone but mosquitos seem to be breeding in the reservoir.
Do you have suggestions for preventing / managing water quality and getting rid of unwanted insects?
Dear Airy,
I have the large two-plant Airy, and the round single plant Airy. The water is both reservoirs smell quite foul. Our watering practice is to allow the meter to drop to the bottom reading before refilling. The plants seem to be healthy and thriving—cream anthurium.
With some flexible tubing I siphoned the water in the larger planter, flushed the substrate, refilled the reservoir to capacity, and drained it again. The foul smell is gone but mosquitos seem to be breeding in the reservoir.
Do you have suggestions for preventing / managing water quality and getting rid of unwanted insects?