A Guide to Water Changes
Maintaining an aquarium is not just about building the correct environment for your chosen species of fish; it’s also about ensuring their health through testing and care. Regular water changes are one of the most crucial parts of keeping an aquarium healthy and thriving. We will be discussing what water changes are, why and when you need them, and how to go about doing them - without flooding the floors!
What Are Water Changes?
Water changes involve removing a portion of your aquarium’s water and replacing it with clean water. Waste, excess nutrients, and decaying organisms in the water release harmful substances like ammonia, nitrites, and nitrates that are toxic to fish in certain quantities. Oceans are frequently replenished by rivers and streams and have natural biological and environmental ways to filter out these harmful substances. Water changes are used to replicate these natural functions while having additional benefits such as oxygenating the water and preventing algae growth.
When To Perform A Water Change?
The size of your aquarium, the type of aquarium (freshwater, saltwater, brackish), what species of fish, plants, and coral you’re keeping, and your filtration system are all factors in when and how frequent water changes should be performed. While many say that 10-20% water changes should be performed weekly, it is best practice to first test your aquarium to see what your parameters are. Let’s get nerdy!
The Nitrogen Cycle
To understand how to test your parameters, you will need to understand the nitrogen cycle. This cycle explains how fish waste and decaying matter convert to harmful substances such as ammonia (highly toxic), nitrites (very toxic), and nitrates (mildly toxic). As you can see, ammonia comes first as highly toxic. This is why it is important to be frequently testing parameters.
The cycle starts by you feeding the tank along with general organic matter breaking down in the aquarium. These processes create ammonia, or (NH3/NH4+). Ammonia is highly toxic to fish and even in small amounts can cause severe illness and death. To understand this in a more rudimentary manner, humans have adapted to use sewage systems to immediately rid our homes of waste and ammonia. The ocean has similar adaptations, but aquariums are not nearly as efficient. Filters and protein skimmers are great ways to combat this issue, but are not 100% efficient. Over time, beneficial bacteria, such as Nitrosomonas, will convert ammonia to nitrites, or (NO2-). The beneficial bacteria naturally inhabit your aquarium and execute this conversion called nitrification. While nitrites are less toxic than ammonia, elevated levels are still toxic and can cause stress and illness. In a similar process, another beneficial bacteria called the Nitrobacter species will convert nitrites into nitrates, or (NO3-) in the nitrification cycle. While nitrates are less toxic than nitrites, elevated levels can still cause stress and illness. This is where the nitrogen cycle ends, and you come in! Let’s discuss how to test for ammonia, nitrites, and nitrates and determine when it is time for a water change.
Parameter Testing
There are four main tests that will determine if your aquarium is ready for a water change:
Ammonia (NH3/NH4+): Highly toxic - Elevated levels could indicate overfeeding, decaying organic matter, or poor filtration. Goal: Undetectable or close to zero.
Nitrite (NO2-): Very toxic - Produced by the middle of the nitrification process. Elevated levels could indicate immature or overwhelmed biological filters. Goal: Close to zero.
Nitrate (NO3-): Mildly toxic - Produced by the end of the nitrification process. Goal: Freshwater Nitrates < 40 ppm (parts per million); Saltwater Nitrates < 10ppm or lower depending on fish species.
pH or KH: Measures acidity or alkalinity of water. Freshwater fish typically prefer pH 6.5 - 7.5 and saltwater fish typically prefer 7 - 12 dKH (degrees of carbonate hardness).
If your parameters are above the goal range listed above, it’s time for a water change! If your water is murky, has a bad odor, or your fish start presenting with symptoms, this is a sign that your parameters need to be tested immediately. If you are on a normal maintenance schedule and these symptoms suddenly arise, check your filtration system to ensure nothing is compromised and speak to your LFS for advice.
If your parameters are in line with the goal range, perform smaller water changes to replenish trace elements in your water. Too many water changes can remove the beneficial bacteria in your water column, subsequently bottoming out your aquarium of bacteria and creating a bacterial bloom.
A common way to determine how much water to remove is through a percent based system. If your testing shows low elevated levels of ammonia, nitrites, and nitrates a good start would be to replace 10-15% of your water with clean water. If your testing shows highly elevated levels, a 20-35% replacement would be a good start. The more frequent the water change, the less drastic of a disturbment to the bacterial environment.
How To Do A Water Change
You’re ready for a water change! Let’s go over the equipment you will need to streamline this process.
- 2 large barrels, preferably on wheels
- Long hose
- Submersible pump (we recommend Sicce pumps)
- Clean water
- Beneficial bacteria
*a hand siphon can be used, but may take longer. A hand siphon is ideal from smaller aquariums.
- Prepare your clean water. For freshwater, depending on your species of fish and the quality of your tap water, use tap water or RO with beneficial bacteria. If using tap water, use a dechlorinator as well. For saltwater, prepare RODI mixed with your choice of salt and test with a refractometer until reading shows 1.020 to 1.025SG (specific gravity). Add beneficial bacteria. Aquavitro’s seed is a great beneficial bacteria that can be used for both freshwater and marine aquariums. Make sure the temperature is aligned to the water temperature of your aquarium.
- Turn off equipment. Turn off pumps, filters, and any other equipment so it doesn’t overheat or run dry.
- Remove water. Place your barrel on wheels next to your aquarium. Place one end of the hose into the bucket, and the other end of the hose connected to the submersible pump into your aquarium. Plug in the submersible pump and pump your calculated amount of water into the barrel.
- During the removal of water, use this time to clean the sides of your aquarium and remove any decaying plants or any other organic matter in your aquarium.
- Remove the submersible pump from the water or kink the hose to stop pumping water and unplug the pump. Dispose of your water.
- Add clean water. Place one end of the hose into your aquarium and the submersible pump into a barrel of clean water. Slowly add the clean water into your aquarium. To limit disruption to your aquascape from the flow of water, place your hand or an object over the flow to evenly distribute it.
- Restart your equipment.
- Monitor parameters. Allow time for the water change to settle and retest your parameters. It is best practice to log your findings every time you test your parameters to find any common spikes or noticeable trends in your aquarium.
Congratulations, you just completed your first water change! We hope this blog ensured the process was as seamless as possible. Water changes are the key to a healthy aquarium and by following these steps on a routine basis, you're sure to enjoy a pristine aquarium with happy, healthy inhabitants. Don’t want the hassle? Let us know and we can do it for you!