Your aquarium water may look clear and clean, but the way your water looks is not the best indicator of the health of your water.
Nitrates and Phosphate Levels
Fish waste and fallen food release nitrates and phosphates into the water. Nitrates and phosphates can build up in the water over time. Elevated levels of nitrates and phosphates will promote algae growth and will stress fish.
Changing your aquarium water on a consistent basis is the most effective way to ensure that the levels of nitrates and phosphates remain low in your aquarium water. You don’t need to make huge water changes. Just do it consistently.
Water Change Frequency & Amount
It’s probably a good idea to change 10% to 20% of your aquarium water on a weekly basis. The amount of water that you should change and the frequency that you should change it will depend on how large and how stocked your aquarium is.
If you have a 10 gallon tank that is crowded with a bunch of fish, you will want to change the water one a week and probably change more than 10%.
If you have a large 75 gallon fish tank and only a few fish, you may only need to change 10% of your water every one or two weeks.
Aquarium Water Changing Recommendations
When you are removing water from your aquarium, use a gravel vacuum to suction waste out of the gravel and rocks. This will allow you to take some extra waste out of the tank while you are removing water.
If you are getting your water straight from the tap, let the water sit for a day or two before you add it to the tank. The water fresh from the tap will contain dissolved gasses that should be allowed to dissipate. This will also stabilize the pH levels of the water before you add it to your aquarium.
Add the water to the tank slowly to avoid disrupting and stirring up the substrate.
If you are doing a large water change, be careful of the temperature of the water when you are adding it back to the tank. Not allowing the temperature of the tank water to change sharply in either direction will spare your fish some possibly fatal stress.