What is a Low Tech aquarium?

A Low Tech aquarium, as its name suggests, is a tank that uses as few technical tools as possible. Often these tanks do not include filtration and heating and only basic lighting, or even no lighting. Inspired by the Walstad method, these aquariums "turn" by leaving mainly the plants and the population of the tank to create a cycle allowing life in the aquarium only through photosynthesis.

What is the difference between the low-tech method and the natural aquarium?

There is no such thing as 100% natural aquarium keeping, the natural side refers only to the means that plants have to act as a natural filter, that is to say that in a well planted aquarium we can do without filtration. . But even in a so-called "natural" aquarium you have to intervene, contain the vegetation, use lighting, compensate for evaporation, feed the fish.

Why is filtration not necessary in low-tech?
In low-tech or natural aquariums, it is the plants that act as a filter. If the filtration does not disturb the balance between axolotls and plants, the plants manage to absorb the ammonium obtained from the excrements of the aquatics, thus preventing the proliferation of nitrites and nitrates. Several scientists have shown that, in aquatic environments, plants quickly absorb nitrogenous matter, in an aquarium the same thing happens. They also found that plants can fix heavy metals as well. The various experiments have shown that aquatic plants could very well replace filters.

Does it seem like low-tech or natural aquariums are dirty?
Absolutely not. A low-tech aquarium is cleaned less often, less siphoning from the ground and less water changes, and the aquarium stays clean thanks to a light agitation that does not stir too much, and thanks to the many bacteria, which take care of degrade waste. A low-tech bin remains clean and the water is not cloudy, but it is certain that it is not a sanitized bin since in low-tech we allow plant waste to decompose naturally and we also use the leaves. dead.

Is it true that in a natural aquarium very few fish or axolotls are needed?
It's like traditional aquarium keeping, you have to avoid overcrowding. The aquarium should be proportionate to the size of the fish. What must count are the needs of the fish, it is necessary to know if they live in groups, to know their size once adult, their ability to reproduce, their aggressiveness or not, their swimming area (groundfish, medium , of surface). Generally most aquariums are overcrowded, it is necessary to make a choice, the choice of their well-being, happy fish are those who do not constantly struggle to defend their territory or to feed themselves and who can hide when they do. feel the need. Here we will rather talk about axolotls, refer to the comfort table for correct measurements.

It seems that you have to feed the fish very little in a natural aquarium so as not to pollute too much, is it true?
No, you have to feed the fish correctly, several times a day in small quantities. We must observe the fish after feeding, they must not have too big a belly and that they do not become too heavy or unable to swim, that is the sign that they are overfed. Afterwards, if there is excess food that falls on the sand, it does not matter, once degraded this food will release a whole bunch of elements that the plants will absorb, it will become a natural fertilizer, snails will also benefit. Finally, the fish should be fasted once a week. In our aquariums, unlike wild life, they are fed regularly. A weekly fast allows their digestive system to rest, it helps keep them healthier and alive longer.

Do you need a large aquarium for it to work well without a filter?

No, it is not mandatory to have a large tank, from 30 liters an aquarium works very well without filtration at all. It suffices to put Ceratophyllum or Elodea, and duckweed so that the environment remains healthy. Obviously, in this kind of tray, you can put either a Fighter, or Killies, or a couple of Dario Dario. Lighting is still necessary for the plants. For maintenance it is as for larger bins. You have to compensate for evaporation, make two or three water changes a year, prune the plants, etc.


2) Aquarium cycling, nitrogen cycle, bacteria:

Is there also a cycling period for a natural aquarium, as in the traditional aquarium?
There is a period during which the ecosystem is set up, the duration may vary depending on the aquarium, but during this period the aquarium is unstable because a host of bacteria gradually colonize the tank. It is better to wait two to three weeks before putting your fish. For aquariums with potting soil the cycling period can be longer, from three weeks to a month or more.


Diana Walstad says you can put the fish in the aquarium from day one, is that feasible?
Diana Walstad doesn't say you have to do it but that she does it, she doesn't say that her way of doing things is the best, she only describes her way of doing things, it's very different. Personally, I do not recommend stocking your aquarium from the first day because that would require increased monitoring of the tank and the aquatic ones. During the first two or three weeks, the ecosystem stabilizes slowly, there is no point in rushing. Why stress yourself out by putting the fish in quickly when you can do it in a relaxed and serene way and take your time ?!

Does a natural aquarium also experience the nitrite peak?
No, in a natural or low-tech aquarium there is no what is called the 'nitrite peak'. Colonization by bacteria occurs gradually, even if there is at the beginning a slight increase in nitrites, the process goes almost unnoticed, this is in the case where there is no powerful filtration and the aquarium is abundantly planted with real aquatic plants.

Why is there no nitrite peak in a natural tank?
In a natural aquarium nitrification is also done but in a much gentler way. As there is no powerful 'biological' filtration with large filter media, which offers immense ground for the proliferation of bacteria, there is also no sudden increase in nitrites. In fact, the increase in nitrites is proportional to the 'filter' masses present in the filtration and to the power of the filter. In addition, in a natural aquarium, aquatic plants participate in the regulation of bacteria and maintain their populations at a reasonable level. An important thing is that pure aquatic plants take up ammonia in the form of ammonium, so there is no significant nitrification.

Is the nitrogen cycle the same as in an aquarium with filtration?
No, the same does not happen with nitrogen in a natural aquarium. In an aquarium with filtration, the ammonium cannot be absorbed by the plants since it is sucked by the filter where, because of the filter media, it is transformed by the bacteria into nitrites and then into nitrates. On the other hand, in a natural aquarium, it is the plants that absorb ammonium directly, so there is no large production of nitrates. In a well-planted, well-functioning aquarium, the nitrate level should be zero. There may, however, be some but at a very low rate, if this happens it is necessary to add plants or replace some.

Can I introduce my fish as soon as my aquarium is planted and put in water?
No, it is better to wait a fortnight after filling it with water. If you find that the aquatic plants are growing well and are healthy, this is where you can start by introducing a few fish. You can optionally test your water to verify that there is no risk to your axolotls.


How long do I have to wait before putting on the axolotls or fish?
It takes two to three weeks for the aquarium to stabilize. It will take a lot of pure aquatic plants and leave the snails at the start. To put the fish, the vegetation must be healthy and lush. Lots of plants means big clumps of Elodea or Ceratophyllum, vallisnerias, fast growing plants (not like anubias) and not that you need lots of different varieties.

I have been offered a product that is supposed to bring bacteria into the aquarium quickly to speed up cycling, is that a good thing?
I do not think it is necessary to inoculate the tank artificially. It is best to let the process take place naturally. By putting plants and gastropods, you introduce bacteria that will multiply, no need to spend money and force nature.

I was told that bringing bacteria was essential?
We can very well do without these products. Bacteria come naturally with plants, snails and water. Our mains water is already full of bacteria which will grow rapidly in a favorable environment such as an aquarium. For bacteria to thrive you need water, light, and a little heat.

In addition to this, you will need to know more about it.

Equipment, mixing, lighting:

I have an aquarium with an internal decanter, how can I remove the filtration?

There are two solutions, either you remove the decanter by cutting the silicone with a cutter, it's very easy, or you remove the filter media and you keep the decanter empty with just the turbine.

Why do you have to stir the water since filtration is unnecessary?

Stirring is often necessary, not always but often, because this allows the nutrients and carbon dioxide to be distributed to the plants, it also makes it possible to homogenize the temperature. But the most important thing is that it helps provide oxygen to bacteria all over the tank. It is thanks to oxygen that bacteria do their job of degrading and recycling waste. It is only when the waste is sufficiently degraded that plants can reuse it. Stirring also prevents the formation of the biofilm on the surface which, if not broken, prevents gas exchange.


I have a 30 liter aquarium with a Fighter, do I have to put a pump for the brewing, is it really mandatory?
Nothing is mandatory, you have to test and do according to the specifics of your baccalaureate. It is true that the Betta does not like the current which tires it out if it is too strong. Try with no current at all, it can work very well or with an enhancer. If your plants are growing well and there is no buildup of waste, your aquarium is viable without mixing.

Can an air pump be used instead of a turbine for brewing?

The ideal is to have a mashing wheel which moves the surface very slightly, or a small internal filter without the filter foams. A bubbler drives out the carbon dioxide and thus deprives the plants of the essential CO2. The bubbler can be useful during hot weather, in case of fish disease, or at the start of the installation of a new aquarium, but that's it. That's the theory, personally, and failing to have a small turbine, I used a bubbler for my 200l, I didn't notice anything abnormal, my plants were exploding. I believe that a bubbler in a large tank does less damage than in a small ... I see the beginning of an explanation.

Can I use my external filter if I remove the filter media?

If the filter is powerful it is not wise. The external filters are generally too powerful and if you remove the filter media the power is even greater, everything in the aquarium is likely to blow up. A strong current is not necessary and if you have scavengers like Ostracods or Aselles, they may either get sucked in or be injured, and fish don't like too strong a current either. A small turbine (ventury) producing a slight current is sufficient.

How powerful should the circulation pump be?

For an aquarium without filtration you do not need a powerful turbine, once the volume of the tank is largely sufficient. But this is difficult to find when you have a small aquarium, for this kind of small tank there are small internal filters that you can clamp and you just have to remove the foam.

I have a small internal filter, does the foam around the strainer create nitrates?
It is quite possible that the foam, as in conventional filtration, produces some nitrates, but this is marginal. If you want to avoid this, just rinse the foam once a week. But if your tank is large, this nitrate level will be insignificant.

I have a small internal filter with different foams, should I keep them?

No, you don't have to keep them, these foams are intended for a traditional aquarium hobby. In low-tech you just need the turbine to make the current. Optionally, you can replace these sophisticated foams with perlon, just to prevent a snail from getting sucked in and blocking the turbine.

Can I use my under sand filter for my natural aquarium?

This is not useful because in a natural aquarium there is a need in the soil for an anaerobic zone. This type of filter, even if practical for small breeding tanks, ends up clogging the substrate quite quickly. It should be remembered that, in the last layer of sand, bacteria live without oxygen and produce CO2 by consuming nitrites, if the soil is too oxygenated, this denitrifying operation does not take place and that would be a shame.

What lighting can we use in low-tech?
Usually the lighting supplied with the aquarium is sufficient. Too much lighting can benefit the algae. In low-tech we use an average lighting of 1w for a maximum of 2 liters. at 1w for 3 liters. The color T ° must be between 6 and 7000K, and the IRC between 80 and 90. Fluorescent tubes are very efficient, it is simply necessary to avoid lighting with the blue color which favors algae. Compact fluorescent bulbs for medium bins are also effective, for larger bins you can add more than one. CFL bulbs for horticultural use are also suitable for the growth of aquatic plants, they give very good results with a longer lifespan, in addition to their low cost. (According to D. Walstad) (
see lighting article ).

How many hours a day should you light your aquarium?
It can vary from 8 to 12 hours a day. If your aquarium is very planted and especially well populated you can light a dozen hours per day.
If you have simple vegetation, and few fish, daily lighting between 8 and 10 hours is sufficient. Remember that the more you light, the more your plants need nutrients and CO2, if these are lacking there is no point in straining the lighting. Lighting a lot is not going to make your plants grow any faster. You have to find the right balance.


I read that D. Walstad advises to take a "nap" of 4 hours in his aquarium, is it really useful?
This is indeed what she advocates. A cut of 4 hours during the day allows the stock of CO2 to be able to be reconstituted. His explanation seems logical to me, and in view of his bins this method works. It also allows you to enjoy your aquarium for longer since it is lit in the evening, when you are at home, after a day's work.

Low Tech suitable for beginners?

Even if the theory is attractive. Featured on many blogs as the ultimate solution combining ecology, well-being of aquarium occupants and economy. The Low Tech tank is not necessarily a good idea for the amateur aquarist. Indeed, this system presented as simplistic by aficionados of the all natural and adapted to the poubellarium requires a certain amount of knowledge in aquarist which is not necessarily mastered by beginners.

And this kind of natural tank will quickly become an adventure "without a net" which could derail this project by a simple disturbance of the water parameters.

So, beginners think twice before taking the all-natural route. Sometimes, it is wiser and more responsible towards your future residents, to opt for a lower volume of water resulting in less maintenance cost than to choose a system that you will not master before several failures. You will need to test the ammonia in your aquarium regularly to be sure that the pollution is well absorbed by the plants.

Here are the experiences of the members

now axolotls in Low Tech

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"So for my lowtech tank I started it two years ago (early 2016). I had originally prepared the aquarium in the classic way with an external filter, and cycled it for about 4 weeks. On a forum I met a person who kept his axolotls in lowtech. He was very criticized on this subject. But his maintenance greatly interested me being a follower of the natural on a daily basis. I read a lot, French articles but especially English. Some had kept fish "fragile" without problem for years with this technique. Despite the fear I took out my filter, I took it to a friend and put it in his aquarium to maintain the bacteria alive and active, in case of concern. I tested my water every day, with an empty tank next to it in case of problems. I never needed it. From the start my tank was heavily planted, a bit of everything , and with a single axolotl at the start to avoid too much pollution when starting up. 6 months after a second joined the baccalaureate. I then put a small internal filter to create a movement of water, it is not mandatory, but the axolotls are not at speeds. I added emerged plants over time, I test new ones regularly, I find it a plus. I drew a lot of inspiration from poubellariums. I have never siphoned off the ground. I never do a water change. I add a little pipe water from time to time to make up for the evaporation. I rarely prune the plants, I like the mess it gives. I observe a lot, the number of snails, where are they, the micro-organisms, the behavior of the axolotls, the state of its gills, etc ... "

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"The plants in submerged I have vallisneria, java moss, lentils, alterantera

Emerged: Monstera, cyperus, dwarf fern, Dieffenbachia, pothos, chlorophytum, lucky bamboo and other dracaena and an unidentified pante. "

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(To come photos of the new 150 x 50 x 60 bin)

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Thanks to Stella Lagriffoul for this sharing. ^^

In addition to this, you will need to know more about it.

In addition to this, you will need to know more about it.

Stella Lagriffoul.jpg