Changing the water in your reef aquarium sounds like an easy task, and for the most part it is. But there are a few steps that need to be taken to ensure that your water change is done properly and all the animals do not become stressed in the process.
In this article we will go over the importance of water changes and some tips on how to perform one. For more details on how to clean a reef tank, check out our blog on Tips & Tricks for Cleaning a Reef Tank.
Why are water changes important?
Water changes remove and dilute harmful chemicals and waste. They also help to replenish vital elements that are needed in a reef tank for corals.
What percentage of water should be changed?
When performing a water change it is recommended to change 10-15% at a time or 20-25% if the aquarium is heavily stocked. Changing a larger percentage of water can drastically alter the levels of calcium, alkalinity and other nutrients in your reef tank causing stress to the fish and to the corals.
How often should water changes be performed?
Water changes should be performed every 1-2 weeks. If phosphates, nitrates, ammonia or nitrites are high then a water change should be performed every 3 days until nutrient levels are back to normal. (Please see Water Quality for Reef Tanks Part 1 for a list of the target ranges for the most important water parameters.) Smaller more frequent water changes will help prevent stress on your fish and your corals by preventing large swings in the water parameters.
What happens if regular water changes are not performed?
If regular water changes are not performed in your reef tank the waste levels may increase potentially becoming toxic to fish and to corals. Even slightly elevated waste levels can stress certain invertebrates that are sensitive to higher levels of nitrates and phosphates. Corals may slow or even stop in growth and begin to lose their vibrant color and become a more brown color. Certain trace elements will also become depleted unless they are dosed separately. (Please see Water Quality for Reef Tanks Part 3 for a list of the most important supplements and additives.)
What is the difference between salt mixes?
There are different salt mixes for different types of aquariums. With a reef tank you will want to make sure to buy a salt mix specifically made for reef tanks and corals. These types of salt mixes will have higher amounts of calcium, alkalinity and magnesium. Try and pick a salt that mixes to your preferred calcium and alkalinity levels in your reef tank.
How to perform a water change?
So how are you supposed to perform a water change? Here are some important tips to follow next time you change your water.
- Make sure to use RODI water to prevent any contaminants from going into your tank from your water source.
- Make sure to heat the fresh RODI water to match the water temperature in your aquarium before adding salt. This part is important because the water temperature will have an effect on the salinity level.
- Add the proper amount of salt recommended to reach your target salinity.
- Carefully follow the instructions for your salt mix. Many need to mix for hours before they are ready to use while others only need to be hand mixed and are ready to use once the water clears. Improperly mixing salt mixes can be dangerous to your tank and can lead to imbalanced levels of calcium and alkalinity.
- Water can be removed from either the main display or the sump. If the sandbed needs siphoning or there is a lot of algae or detritus needing to be removed from the main display then it is best to remove the water from the display. However the sump will also need regular maintenance since detritus and algae can also build up there. Choose whichever area needs the most attention and do not forget to alternate between the two.
Water changes are an essential part of a healthy aquarium, they dilute the nutrient levels in your tank and help replenish vital elements. Making them a routine task will help keep your aquarium healthy and help all the inhabitants thrive.