The Freshwater Aquarium Water Guide

When thinking about setting up your aquarium, you may not pay too much attention to the water since most people believe there are other things that are more important like the equipment, right? You cannot be more wrong.

As strange as it might seem, if the chemistry of the water is not balanced, your fish and plants will not survive, no matter how expensive your devices. Trust me, I experienced it the hard way!

Aquarium Water

The parameters of the aquarium water can be adjusted naturally or by using chemicals, according to the type of fish you want to keep.

While some hardy fish can live in any water, others have specific requirements and they will not have a long life unless you fulfill them.

Note: If you are a beginner, I would suggest you getting a low maintenance fish for a start.

To see if the water in your tank is right for your fish, use testing kits to measure the pH and any chemicals.

In general, the water from your tank is more sensitive in the first weeks after you set up the tank; after that it’s easy to maintain balance.

Parameters of the Water

Freshwater Aquarium Water PH Level

PH is the acidity or alkalinity of the water and many hobbyists have difficulties in establishing the balance.

Most types of fish require strict levels of pH, therefore you need to test the water every few days.

If your fish require neutral pH (7) you are lucky considering this level is easiest to establish and maintain.

Otherwise, you will have to use chemicals and adjust the decorations in your tank; for example, some stones can influence the PH of the aquarium water.

Ammonia and Nitrites

Freshwater Aquarium Ammonia and Nitrite Level

Ammonia and nitrites are naturally produced by fish and if their levels are not controlled they can easily become toxic.

Ammonia will appear in the water from fish waste and is eliminated and transformed into nitrites by the filter.

Since nitrites are toxic, they will be turned into nitrates that will not cause any problems to the fish.

If you notice an imbalance in these parameters, you need to perform daily small water changes and monitor the levels closely.


Nitrates are generally harmless, but they can become a problem in the long term.

If they accumulate in the water they will become toxic.

To prevent this, you have to make sure you have enough plants in your tank to create a natural ecosystem; the chemical balance of the water will be maintained with little to no effort.

All you have to do is perform weekly water changes to remove part of the nitrates.

KH and GH

Freshwater Aquarium GH and KH Test Kit

KH and GH are the carbonate hardness and the general hardness of the water.

These parameters need to be balanced according to the preferences of the fish and any imbalance can destroy the entire population of the tank.

You should pay special attention to the water that you introduce in the tank; test the KH and GH every few days to see if any chance occurs.

Also, these parameters are directly connected to the pH of the water.

** The higher the pH, the higher is the level of GH.

You can purchase a KH/GH test kit at any LFS or even online. My recommendation would be the KH/GH test kit by API.

Changing the Parameters

If you notice your fish do not have an appetite or they start to lose their pigmentation, there might be a problem with the parameters.

In this case, you will need to adjust them until you reach the desired level.

Find out what levels your fish need and take into consideration changing the plants. Seriously Fish is a good website to find out about different fish needs.

In the beginning, it is not recommended to change the entire amount of water.

This will require a new cycle, which means that your fish will be moved to another tank for the next few weeks.

Start by changing small amounts of water every day; make sure to test the water in the tank as well as the water you want to introduce.

Also take note…

Freshwater Aquarium Filter

Do not change the filter, especially in the middle of the process.

The bacteria present in the filter will actually help you establish the suitable parameters and it will clean the water from any toxic substances.

If you have rocks or corals in your tank, think about removing them before they increase the pH of the water.

There are no strict rules on how you need to take care of the water in your tank.

Every single element, from the fish to the plants to the substrate can influence the parameters.

The only method is to experiment with different levels and see what works best for your aquarium.

To sum it up…

I can’t stress enough the importance of your aquarium water. You should always ensure the water are optimum for your plants and fishes.

To do this, you need to constantly testing and maintaining. Good luck!

If you have any question, feel free to post it below or you could post your question on The Aquarium Guide FB page.

1 thought on “The Freshwater Aquarium Water Guide”

  1. Thanks for your article. i will use it to maintain my first fresh water aquarium that i’ve had now for 3 weeks and all is well so far.


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