How To Clean a Fish Tank

Learning how to clean a fish tank correctly is essential for keeping your new fish healthy and maintaining safe water conditions.

Here are some key points to consider when cleaning a fish tank.

How To Clean a Fish Tank

To properly clean a fish tank, use dedicated equipment and follow a step-by-step process to remove waste while protecting beneficial bacteria.

Clean your fish tank using these steps:

1. Wash your hands thoroughly before putting them in contact with fish tank water.
2. Turn off your filtration, heater, and lighting.
3. Remove decorations from your fish tank and place them in a separate bucket or on a towel. Scrub décor using a designated scrub brush or toothbrush.
4. Scrub the sides of the fish tank using an acrylic or glass scrub brush.
5. Place a siphon into your fish tank and start the flow into a bucket.
6. Move the siphon up and down, taking in a small amount of substrate at each spot. Allow it to circulate briefly, then lift the vacuum to break the siphon.
7. Move the siphon across the entire bottom of the tank.
8. Remove your tank’s filter media (sponges, balls, floss, or rocks) and rinse them in the bucket of waste water. Do not replace filter media unless it is falling apart.
9. Rinse and fill your bucket with fresh tap water. Use a thermometer to ensure it matches your tank’s temperature.
10. Add water conditioner according to the manufacturer’s instructions, treating only the water in the bucket.
11. For salt systems, add the correct amount of salt and allow it to circulate for five minutes.
12. Add fresh water slowly back into the main tank.
13. Return décor to the tank.
14. Turn on lights, heater, and filtration. Filtration may need to be primed—refer to manufacturer instructions.
15. Wash your hands.

How Often Should You Clean a Fish Tank?

How often you should clean your fish tank is based on water quality, tank size, and the number of fish.

Fish tanks must be cleaned on a routine basis to remove waste and provide clean water. Cleaning is especially important during the early stages of a tank setup to complete the nitrogen cycle, but established tanks still require regular maintenance.

The best way to determine if your schedule is adequate is to test your water chemistry. For established tanks, basic recommendations are a 10% weekly water change or 25% every other week.

If any of the following parameters are above range, perform a water change:

• Ammonia > 0.25 mg/L
• Nitrite > 0 mg/L
• Nitrate > 20 mg/L

Always use a water conditioner when adding tap water to remove chlorine.

If you are concerned about water chemistry, contact your fish veterinarian.

Ignoring or performing inadequate cleanings can lead to health issues or death in fish. Buildup of debris, excess food, and waste can increase ammonia levels, which are toxic.

Do You Take Fish Out of Tanks When Cleaning?

Do not remove fish when cleaning a fish tank because it can cause unnecessary stress.

If you clean a fish tank properly, your fish will not be in the way.

The only reason to remove your fish is if the substrate smells like rotting eggs when disturbed, which indicates the presence of toxic hydrogen sulfide. In this case, you will need to remove the gravel and replace all the water.

Move your fish into a holding tank with filtration to give them adequate space while you perform a deep clean.

How To Safely Clean Your Fish Tank

To safely clean a fish tank, protect your fish, equipment, and yourself throughout the process.

• Prevent fish from entering the siphon. If they do, quickly lift the siphon above the water line so the water flows back into the tank.
• Always turn off all electronic components when cleaning. You can still run an airstone if you are concerned about fluctuating oxygen levels due to heavy plant or algae growth, or if your fish are lethargic or recovering from a gill-related disease.
• Never replace more than 50% of your tank water at one time. Large water changes can cause sudden shifts in temperature, pH, and water chemistry that may stress or harm fish.
• Monitor sump systems to avoid overflow. If your system has a sump, it may back-siphon and overflow. Be sure to break the siphon or turn off access to the sump during cleaning.
• If you have open cuts or sores, avoid contact with tank water. As with any pet, there is a risk of communicable diseases, though few are associated with fish. Zoonotic mycobacterial infections are the primary concern and can cause non-healing skin lesions.
• Do not allow children or immunocompromised individuals to handle tank waste.

Freshwater Fish Tank vs Marine Fish Tank Cleaning

Cleaning freshwater and marine fish tanks follows the same process, with a few additional considerations for saltwater systems.

The main difference is working around live coral and marine species in saltwater tanks. These animals cannot be removed during cleaning and must remain in the tank. You may need to gently shift them to vacuum underneath.

What You Need To Clean a Fish Tank

To clean a fish tank properly, you need tools that help remove waste, maintain water quality, and protect your fish.

Water Quality Test Kit

Testing your tank’s water chemistry tells you when it’s time to perform a water change. Test at least once a week with a water quality test kit and refer to recommended parameter ranges.

Tap Water Conditioner

Unless you are using bottled spring water or reverse osmosis water, you must treat tap water with a water conditioner to remove chlorine and chloramine, which are toxic to fish.

Reverse osmosis (RO) water is filtered to remove most particulates, including ions that affect hardness and alkalinity. Depending on your system, it may also remove chlorine and chloramine.

Gravel Siphon

A gravel siphon removes waste buildup from substrate, which is essential for keeping your tank clean. Simply stirring substrate is not enough.

These tools may take practice to use effectively, so expect a learning curve.

Algae Scrubber

Algae growth is normal and can indicate a healthy tank. Use an algae scrubber to clean tank walls, choosing the correct type for your tank material.

Glass tanks can handle more abrasive algae scrubbers, while acrylic tanks require softer sponges to avoid scratches.

Thermometer

A thermometer ensures that new water matches your tank’s temperature to prevent stress in fish. Infrared thermometers allow quick readings before adding water to the tank.

Refractometer (Saltwater Tanks)

A refractometer measures salinity in saltwater systems to ensure proper balance before adding water back into the tank. A quick check with a refractometer is essential to ensure your system’s salinity stays within range.