Open your aquariums! The guide to open tanks and emergent plants
F. MattierShare
Have you ever felt that strange impression, looking at a classic aquarium with its black plastic lid, of looking at nature through a closed porthole? As if the ecosystem was "kept under glass"?
There is a freer, wilder, and terribly more effective approach for the health of your plants: the open aquarium.
Today, I invite you to unlock the latch and let your little aquatic world breathe. It's an aesthetic choice, certainly, but above all a biological choice of "common farmer sense" for your Low Tech.
Let's look together at why your plants dream of sticking their heads out of the water. 🧐
1. Unlimited access to the CO2 buffet 💨
This is the unbeatable biological argument. In a closed aquarium, aquatic plants must fight to capture dissolved CO2 in the water. This is often the limiting factor for their growth.
But as soon as a plant breaks the surface in an open aquarium, the magic happens. In open air, CO2 is abundantly available (about 400 ppm versus trace amounts in water). It's like going from breathing through a straw to a big breath of fresh mountain air.
The result?
- Explosive growth.
- Stronger leaves.
- And the holy grail: flowering.
Some plants in our catalog are champions at this. The Limnophila rugosa (Om Kop) completely changes appearance once above the surface to offer small purple flowers. Likewise, the Microsorum (Java Fern) loves to live "dipped", roots in the water and leaves in the air (ideal for paludariums).
🔗 Om Kop (Limnophila rugosa)
🔗 Microsorum pteropus (Java Fern)
2. The pleasure of aquatic gardening (without complex soils!)
The open aquarium transforms your tank into a true indoor garden. You no longer just look at a glass pane, you interact with a water feature.
This allows the integration of formidable purifying plants. You surely know Pothos or Monstera? But do you know the Aquatic Mint?
It's a local plant we love at Aquazolla. Placed soaking, it develops a dense root system that pumps nitrates at an incredible speed, while delicately scenting the room when you brush it.
🔗 Aquatic Mint (the queen of purification)
And what about the substrate?
No need for expensive technical substrates that deplete in 6 months and need replacing. Why complicate and spend when you can keep it simple and sustainable?
At Aquazolla, we advocate "common sense." We stick to Loire sand or pool filtration sand. Plant roots, especially those that emerge, are powerful. They will seek nutrients where they are: in the "mulm" (waste digested by your snails). It's the cycle of life, free and self-sustaining.
3. The lighting question: take height 💡
An open aquarium often means new lighting. If you remove the cover with built-in neon lights, you'll need to install an LED strip or a clip lamp.
Little tip: install your lighting higher than usual (15 to 20 cm above the water).
Why?
- To give plants room to grow out of the water without burning.
- To create a beautiful play of shadows and light in the room, turning the aquarium into ambient lighting.
4. Evaporation: make it a strength 💧
"Yes but Mattier, the water will evaporate!"
That's true. But in a Low Tech aquarium, evaporation is your ally. It cools the tank in summer.
The trick is simple: regularly top up with rainwater or osmosis/demineralized water. This prevents concentrating lime in the tank. It's the perfect opportunity to simulate a little rain that will delight your residents.
5. Secure the perimeter: stop escapes! 🚧
It's the number one legitimate fear. If it's open, will they jump?
The "Zero Risk" option: the Critter Aquarium
If you want to sleep soundly, the radical solution is to switch to the fishless aquarium. With only shrimp, water lice, and snails, the risk of jumping is almost zero. It's the most "Zen" approach and fascinating to watch.
If you have fish
Some (Killis, Bettas...) are jumpers. For them, the open aquarium requires safety: the floating plants.
They form a natural "green lid" that secures shy fish and prevents jumping. You have plenty of choices:
- The classic Salvinias for their graphic look.
- The Frogbits for their beautiful hanging roots.
- The Large duckweeds (Spirodela polyrhiza) if you want a particularly dense and deterrent mat.
🔗 Salvinias (floating plant)
🔗 Large duckweeds (Spirodela)
And the snails?
Rest assured:
- Malaysian Trumpet Snails : they are wise. If they try to mass exit, it's an alarm signal (pollution). Otherwise, they stay in the substrate or on the glass.
- Ramshorn snails : they are not carpet adventurers either. A ramshorn snail will faithfully stay in the water to clean your glass and plants.
🔗 Malaysian Trumpet Snails (the tillers)
🔗 Ramshorn snails (the colorful cleaners)
Conclusion: let life overflow!
Switching to an open aquarium means accepting that your ecosystem doesn't stop at the glass. It's seeing a dragonfly land on an emergent stem, it's enjoying a clean aesthetic.
It's, ultimately, trusting nature to take its place, its full place.
So, ready to lift the lid? 😉




8 comments
J’ai également une Mimi très cool sauf pour les plantes 😤 donc je mets de l’huile essentielle de citronnelle (2 gouttes environ) autour de l’objet interdit, ça fonctionne bien 👍
Bonjour , c’est tellement vrai…j’ai un aquarium de 30 litres pour le plaisir des yeux, sans poisson. Je l’ai couvert un jour car ma Nana, installée sur ma commode, faisait trempette- papate prélevant des plantes de surface. Le résultat ne s’est pas fait attendre, l’eau est devenue trouble et ne sentait pas bon, j’ai cru tout perdre. Dessus enlevé, changement de 3 bons verres d’eau et tout est revenu au bout d’une petite semaine. Solution trouvée pour Nana. Merci encore pour tous vos conseils.
Bonjour , c’est tellement vrai…j’ai un aquarium de 30 litres pour le plaisir des yeux, sans poisson. Je l’ai couvert un jour car ma Nana, installée sur ma commode, faisait trempette- papate prélevant des plantes de surface. Le résultat ne s’est pas fait attendre, l’eau est devenue trouble et ne sentait pas bon, j’ai cru tout perdre. Dessus enlevé, changement de 3 bons verres d’eau et tout est revenu au bout d’une petite semaine. Solution trouvée pour Nana. Merci encore pour tous vos conseils.
Oui Mattier , 7 aquariums en lowtech et aucuns de couverts , et quel plaisir de circuler et de regarder nos aquariums par le dessus ,contact direct avec les poissons et les plantes . très très peu de changement d eau juste remettre à niveau car ça s’évapore rapidement . et les plantes et poissons se portent à merveille . D’accord à 100% de votre vision de l aquariophilie . Merci Mattier . Joël
Ja,sie haben vollkommen Recht,ein.offener behälter erweitert das Spektrum der pflanzen pflege enorm,und sieht auch noch wunderschön aus,wenn sich der unterwasserdschungel an der Wasseroberfläche vorgesetzt.l.g.rs