Why Water Changes Are Important
The Role of Water Quality in a Healthy Fish Tank
Maintaining a healthy fish tank isn’t just about feeding your fish and ensuring the filter is running smoothly; regular water changes play an important role in the upkeep of your aquatium. Over time, waste products, uneaten food, and other organic materials accumulate in the tank, leading to the buildup of harmful substances like ammonia, nitrites, and nitrates. These compounds can be detrimental to fish health, causing stress, illness, and even death if not properly managed.
Common Water Contaminants
Even with a filteration system in place in your tank, over time, several contaminants can still accumulate in the water:
Ammonia: Produced from fish waste and decomposing food, ammonia is highly toxic and can cause stress, respiratory issues, and even death if levels rise too high.
Nitrites and Nitrates: As part of the nitrogen cycle, ammonia is converted to nitrites and then to nitrates. Although nitrates are less harmful, high levels (>40 ppm) can still stress fish and increase their susceptibility to disease.
Other Organic Compounds: Organic materials, like plant debris and uneaten food, gradually build up, clouding the water and potentially encouraging algae growth.
If your tank is happily cycled, the first two contanimants should be managed by the beneficial bacteria, but the latter two contanimants will still build up over time. That’s where the water changes come in. Regular water changes will help to dilute and remove these toxins, ensuring a cleaner and safer tank environment. Additionally, the fresh water helps to replenish essential minerals and nutrients that may have been depleted, supporting the health of both fish and plants within the aquarium. If your tank is not cycled yet, check out our posts on cycling your first fish tank and also our more in dept guide on how to do a fishless cycle.
Impact of Poor Water Quality on the Fish Tank
Poor water quality doesn’t just look unpleasant; it can have serious health impacts on your fish. Fish living in subpar water conditions are more prone to stress, which weakens their immune systems and increases the risk of illness. Unhealthy water can also affect the plants, live rock, and other elements of a tank ecosystem, ultimately making the tank less stable. It’s therefore important to stay on top of water changes, at a rate that’s suitable for your tank setup, to keep the water not only looking (and smelling) good for you, but also to help minimise the onset of ill health of your tank inhabitants and plants.
How Often Should You Change Fish Tank Water?
The frquency that you’ll need to change water will vary from tank to tank. Some are set up so that they virtually never need to have the water changed, others might require a weekly change. Several factors influence this schedule, including tank size, fish population, and filtration efficiency.
A General Guide for Fish Tank Water Changes
For a freshwater fish tank, a common recommendation is to change 10-25% of your aquarium’s water every one to two weeks – these are known as partial water changes. This is a good place to start while getting a feel of the routine that will be needed for your tank.
For a saltwater tank, these often demand more frequent water changes due to the delicate balance of marine ecosystems. A good place to start for a marine tank would be a 10-20% water change weekly.
Small Tanks vs. Large Tanks
Smaller Tanks (under 35 litres/10 gallons) are more susceptible to a rapid build up of toxins due to their smaller water volume. Therefore, if you have a fair number of fish in a small tank, you might find that increasing the water changes to a 20-30% water changes weekly will help to maintain a more stable environment.
Larger Tanks (over 190 litres/50 gallons) have a greater water volume and can therefore dilute waste more effectively. This is why a larger tank can actually be easier than a smaller tank when getting started in the hobby. In such cases, you can likely get away with a 10-20% water change every two weeks. Though do use a water test kit more regularly while the tank is maturing so you can get a feel for what frequency is needed.
Planted Tanks vs. Unplanted Tanks
Planted Tanks: Aquariums with live plants benefit from the plants’ natural filtration abilities, as they absorb nitrates and other waste products (which they use as fertilser to help them grow). This can allow for less frequent water changes, such as 10-20% every two weeks. Some heavily planted tanks, with only a small number of fish in them, can go a very long time between water changes – mimicking a normal ecosystem when done correctly.
Unplanted Tanks: In contrast, tanks without live plants, waste accumulates more readily, necessitating more frequent water changes. A 10-25% change every one to two weeks is typically recommended to maintain water quality.
Remember, the above frequences are only a general guide. It will be important to regularly test your aquarium’s water parameters, such as ammonia, nitrite, and nitrate levels, to get a clearer picture of your tank’s specific needs and to help you adjust your water change schedule accordingly.
Factors That Influence Water Change Frequency
By now you will have a sense that exact water change frequency is pretty unique for each tank. There are a few additional factors that can also impact on this:
Fish Species and Population Density
The type and number of fish in your tank significantly affect water quality. Larger fish and species that produce more waste (such as goldfish and certain types of cichlids) add more to the tank’s waste load, resulting in a faster accumulation of ammonia and nitrates. The rate of waste accumulation is also affected by the stocking levels of a tank. Expectedly, a heavily populated tank will also experience quicker waste buildup, and thus require more frequent water changes to maintain safe levels. In contrast, tanks with fewer, smaller, or lower-waste-producing fish may need less frequent changes as the waste buildup is slower.
Filtration System and Tank Maintenance
A well-functioning filtration system will do a large part of the water-cleaning load when it comes to removing waste and helping break down harmful compounds. While a high-quality, well-maintained filter can reduce how frequently you need to change the water, it can’t eliminate the need entirely. A larger filter can help to reduce this frequency (however, do keep flow rate in mind when choosing your filter size in terms of the happiness of your tank inhabitants), as can keeping your filter well maintained. Just like your tank water, your filter media will need cleaning from time to time (always using dechlorinated water), to be able to do its job properly. Together, these filter consdierations will help to manage waste levels wilthin the tank, but should work alongside (not replace) your water changes.
Water Testing and Monitoring
Regular water testing of your water parameters is invaluable for understanding your tank’s specific needs, and, more specifically, when a water change is due. Elevated levels of ammonia, nitrites, or nitrates indicate that waste is accumulating, signaling it’s time for a change. Using water test kits will allow you to monitor these parameters and adjust your water change schedule accordingly. This proactive approach will help you to keep your tank’s ecosystem stable and healthy. I would recommend testing your water parameters 1-2x a week while you are getting a feel of your new tank, or after new tank mates are added, so that you can make sure that the tank stays stable and while you are dialing in the needed cleaning frequency.
How to Change the Fish Tank Water
A Step-by-Step Guide for Safe Water Changes
Changing your fish tank’s water might seem straightforward, but doing it properly will help to avoid unnecessary stress to or harming of your fish. Here’s a step-by-step guide to help you change the water safely and effectively in your tank.
Tools Needed for Water Changes
Before you begin, gather the necessary tools:
Siphon or Gravel Vacuum: For removing water and cleaning debris from the substrate. The gravel cleaner attachment also enables you to start the water flow without needing to suck on the end of the hose:
Fill the end with water. Raise it above the water level so that water starts to flow through the hose. At this point cover the end of the hose with your thumb – this should stop the water flow. Now, lower the gravel cleaning end back into the water, allowing the water bubbles to escape. At this point, you should be able to remove your thumb and the water will start to flow out of the tank and into your bucket.
Bucket: Dedicated to aquarium use only, to avoid any potential contaminants. I recommend picking up a white-coloured bucket. It will make it much easier to see if you have accidently sucked up any small tank inhabitants before you throw the water out.
Water Conditioner: To neutralize harmful chlorine and chloramines in tap water.
Thermometer: To ensure the new water matches the tank’s temperature. This is an important step to make sure that the fish are not shocked when adding water back into the tank. The shock can be enough to kill some of the more delicate species.
The Step-by-Step Guide and Tips for Minimizing Stress on Fish
Changing water can be stressful for fish, so aim to minimise the disruption caused. Here are some tips:
Turn off Tank Equipment: Temporarily turn off filters, heaters, and lights. This prevents damage to the equipment and helps keep fish happy and calm.
Use the siphon to remove the necessary water volume from your tank. If you have gravel substrate, press the gravel cleaner into the substrate to suck up debrey that might have fallen between the gaps.
(optional step) Wipe down the glass and any internal decorations with a sponge to minimise any algae build up.
(optional step) Clean the filter media. With the filter turned off, open it up and remove the media. Squeeze this into the (old) tank water in the bucket. Squeeze it a few times until it does not add more gunk into the bucket. Then replace within the filter. (That’s it!)
Get new water ready. Fill bucket from your water source. If tap water, then add dechlorinator to make it safe for both the good bacteria and the fish. Aim for the new water temperature to be as close as possible to that of your fish tank.
Replace the tank water: Using a gentle flow (to not shock the fish and to try not to distub any sediment still in the tank), pour the new water into the tank. You might opt to use the siphon for this. Other suggestions are to try pouring through a sieve, or onto a decoration in the tank to break the impact on the substrate.
Turn the Equipment back on. And you are done!
FAQs on Fish Tank Water Changes
To make your aquarium maintenance routine smoother, here are answers to some common questions about fish tank water changes, to help you better understand the process and its importance.
How Do I Know If My Tank Needs a Water Change?
Signs that your tank needs a water change include cloudy water, unpleasant odors, or visible algae growth. However, the best way to know is through regular water testing. Elevated levels of ammonia (>0 ppm), nitrite (>0 ppm), or nitrate (>40 ppm) indicate that waste has accumulated and a water change is necessary. Testing water weekly can help you anticipate needs before any visible issues arise.
Can You Change Too Much Water at Once?
Yes, changing too much aquarium water at once can shock your fish, especially if there’s a drastic change in temperature, pH, or other water parameters. Most aquarists recommend changing no more than 25-30% of the tank’s water in one go. Larger, more frequent water changes are only advisable for emergency situations, such as a sudden spike in toxins. For routine maintenance, sticking to smaller changes on a regular schedule is safer and less disruptive.
What Happens If I Skip a Water Change?
Skipping water changes can lead to the gradual buildup of toxins which can negatively impact fish health over time. Fish exposed to poor water quality are more prone to stress and illness, as their immune systems weaken. Consistently skipping water changes may also disrupt the biological balance in the tank, causing issues with algae growth, pH level, and aquarium water clarity. It’s best to keep on scedule as much as possible to help avoid this.
In Summary
Maintaining a regular water change routine is one of the most beneficial things you can do to keep your fish healthy. Not only does it help remove harmful toxins, but it also replenishes essential nutrients and keeps water parameters stable, fostering a balanced ecosystem for your fish and plants.
By paying attention to factors like fish species, tank size, and filtration system, you can customise a water change schedule that suits the specific needs of your aquarium. Regular testing will also ensure you’re staying ahead of any potential issues. Indeed, it’s an easy go-to first step when something feels off about your tank, or if your fish are looking a litte unhappy. Sometimes a water change can be enough to bring things back to normal, without the need for extra equipment or chemicals.
Ultimately, taking the time to implement a consistent water change routine can make all the difference in your aquarium’s overall health and longevity.
