Water change Aquarium – harmful or not?

Carry out the water change correctly

You have an aquarium and the water is slowly changing colour? Then it’s time for fresh water. But be careful, there’s a lot of things you can do wrong when changing water. It is strongly discouraged to change the entire water system.

The complete water exchange damages plants and fish

ronymichaud / Pixabay

Every water has its own characteristics. There are useful bacteria in the water, it has its own PH value and a certain degree of hardness. If you change all the water, animals and plants will suffer a shock and die in the worst case.

If you buy new fish, you will usually get a bag that is filled to one third with water. The remaining part of the bag is air. The air is not there so that the fish can breathe better, but so that you can slowly accustom the fish to the new water. This way you are able to fill the bag with the water of your aquarium with short pauses and slowly introduce the fish to the new water. The same principle also applies to the aquarium.

Why do you have to change the water?

In nature, for example, the river has a current, i.e. the water is constantly changed. At the lake there is also movement and rain falls regularly, which brings fresh water. Anyone who has had a few fish with him knows how much they enjoy doing their business. A lot of fish excrement, decaying plant remains and also food leftovers on the aquarium floor are a burden on the water. The factors mentioned above cause the water quality to tilt negatively and make it absolutely necessary to add fresh water regularly. In addition, with fresh water you add valuable minerals to the tank, which are also needed again. By the way, the fish excrement is not only harmful.

Various bacteria and animals such as shrimps process the fish excrement and mulm. Mulm can lie on the bottom as a residue or be dissolved in the water. But Mulm is not necessarily harmful. Various substances must be broken down in the aquarium, there are bacteria for this purpose, which in turn settle in the mulm. Thus pollutants are decomposed in a natural way. So, if you constantly change your water like a madman and run after the fish with a jug so that they just don’t put it in the tank, this is not effective.

Mulm keeps the cycle in the tank stable and also provides food for micro-organisms, which again serve as fish food. I will write an extra guidebook about Mulm. Fact is, too much Mulm harms, too little also. If you remove the mulm with a mulm sucker, for example, only take away a good third of the mulm. This way the amount of bacteria remains stable and you don’t have to worry.

How often do you change the water?

You’ve probably fought your way through a thousand forums so far and everyone has given you great advice. Unfortunately there is no clear answer to this question. A change every few months is too rare. I myself regularly fill up the evaporated water and clean the pool every 3 weeks. During this process it also loses some water and I can add fresh water. However, I do not add the water directly, but prepare it beforehand with a water starter.

On which factors does the frequency of change depend?

Depending on how many animals and plants you have in the aquarium, the frequency or interval of change also varies. If you fertilise once a month, the mulm also absorbs and stores this fertiliser. This is partly not bad at all, because if there are too few nutrients the mulm releases them again. But if there is no deficiency, then it stores too many nutrients. The less often you make the change, the more water you have to exchange. Therefore, a method where a little bit of water is changed regularly is in my experience the best.

  • Quantity of stocking of plants and fish
  • Quality of the water filter
  • Frequency of fertilization
  • Size of the aquarium
  • Biosystemic balance
]With the balance of the biosystem I refer to the fact that there are not only animals that leave fish excrements, but also other useful creatures. Catfish, mussels, snails, shrimps and, for example, freshwater shrimps help the balance and improve the quality and cleanliness of the water.

Temperature during water change

Care should also be taken with the temperature. Water from the tap is usually ice-cold. As an attentive aquarist you have already noticed that different creatures have different requirements regarding temperature, pH-value and water hardness. Some fish or plants react particularly sensitively, others take slight fluctuations relaxed. But for example with colourful tropical and exotic fish coming from warm countries, ice-cold water is a real shock. Now you are probably wondering how to get the water warm and if this is even necessary.

Depending on how much water I change, the more I take it into consideration. My first step when adding a new fish or plant species is to create a water value matrix. Here I take all existing values and look in which area they overlap. The range of values that remains at the end is my perfect water value. If I have chosen a fish which does not fit in, then either a new tank must be built or you have to do without it. Otherwise you do not do yourself or the creature any favours, no matter how pretty the fish is.

Now that I have a perfect water temperature, I not only set the basin heating to the optimal value, but also prepare my water. For small amounts of water, like filling up with evaporated water, I accept the cold when changing the water. The pool as a whole has so many litres in my case that the temperature fluctuation is minimal. If I fill up larger quantities, I take a tub or a bucket. Here the cold water comes in and hot water from the stove. Stir well, put a water conditioner on it and off to the pool.

Pollutants during water change

Water from the tap can contain various pollutants such as heavy metals. Especially with warm tap water, larger quantities of copper are often found. But copper is not the only problem. Other pollutants are chlorine, chloramine, lead and zinc. Here again the water conditioner or water starter is used. This not only neutralises the pollutants, but also adds valuable vital substances.

I use AquaSafe from Tetra and am very satisfied. It makes the water as fish-friendly as possible, and the useful bacteria in the mulm take over the rest afterwards. The care colloids protect the fins, mucous membrane and gills of ornamental fish. Vitamin B is not only good for health care but also reduces the stress level of the fish. Iodine and magnesium promote the fast and healthy growth of the aquarium inhabitants. AquaSafe can be used for freshwater fish and for seawater. It should be said that there are other products available for this purpose. These are not bad, I just haven't tested them and therefore I cannot say anything about them.

How do I change the water?

The water change is actually quite simple. But be careful with old pipes in old buildings. These can, but do not have to cause significantly higher pollution. A water test provides clarity here. You can either lead the water directly into the pool - with a pump or hose or, like me, fill in buckets in stages.

The pumping out

But first we have to remove the old water depending on the degree of pollution. Place a bucket or construction tub next to the pool and suck the water briefly. If you want to clean the bottom of the pool, then put a mulch bell on the front of the hose side that is in the pool. So that your water change does not end in a mess or a life-threatening situation, prepare enough rags and a second bucket in which you can put the hose. You have to be careful with the electrical system, either it is placed so that nothing can go wrong (desirable) or you switch it off temporarily.

It is always faster

If the process is not fast enough for you or you want to do other things on the side, you can of course take a submersible pump and put the hose directly into the toilet or the garden. This variant saves you time but is also very dangerous if you forget the process and the fish suddenly run out of water. This happens to you only once. Old water belongs in the toilet or the garden. In the washbasin and the bathtub you will clog your pipe in the long run, because plant remains and other dirt will collect.

A little tip

Filling into the basin must be carried out carefully. If you hit plants, sand or fish with a hard jet or a surge from the bucket, it can quickly be over. In order not to flush large holes in the sand, you can place a plate on the bottom of the aquarium and aim at it. This way nothing will be washed away and nobody will suspect that the water change has just been done.

The last step of the water change

When the water has been filled in, the water values must be measured as always. Whether you do it electronically or with a paper strip is a matter of taste. The most important values are:

  • Temperature
  • PH value
  • Water hardness
]Bring all values back into balance and your fish are happy. But be careful not to let the PH level drop too quickly. It's best to stick to the manufacturer's instructions, then you won't do anything wrong. If you put the additives into the water, stir well afterwards, otherwise you will get different zones with different values. By the way, as a small piece of advice: You can also lower the pH value naturally, for example by adding oak leaves or the boiled brew from it.

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