Aquarium Filter Current Too Strong – How to fix this issue?

Creating a steady current in your aquarium helps circulate and evenly distribute water. This ensures that the tank maintains a stable temperature and optimal oxygenation level. Some fish require slower-moving currents because they aren’t strong swimmers. Strong filter current can cause problems for the fish and plants. So, how can you fix this issue?

There are several ways to reduce aquarium filter current strength. You can decrease filter power and current strength by adding decorations like rocks, cave structures, and plastic plants. Adding motor speed control can also help reduce the strong current flow. 

Discover more ways to fix a strong filter current in this guide. Let’s get started!

What To Do If The Filter Current Is Strong For Your Fish

Fish can’t swim freely when the filter current is too strong in your tank. Here are the steps you can take to fix this:

Buy A Pre-Filter Sponge

Buying a filter sponge is one of the most cost-effective and simple ways of reducing filter strength. Wrap the pre-filter sponge around the nozzle of your aquarium filter to decrease the flow.

Buy A Filter With Adjustable Flow

If you don’t like your filter, then buy a new one. You can buy filters with adjustable flow mechanisms. These filters let you achieve the perfect flow for your fish. They are incredibly cheap, and you can find them easily on Amazon. If you have a five or a ten-gallon tank, you can pick up an adjustable filter for $10-$30!

Use Decorations To Reduce The Flow

You can use decorations and plants to decrease the current flow and strength. Deciding your tank décor can be a fun process. You can add artificial caves, rocks, and plastic plants to reduce the filter current strength. Your tank should also have several hiding places for your fish. If you want something natural, then you can use driftwood or plants.

Some great plants for reducing current strength are betta bulbs, java fern, anubias, and anacharis. Alternatively, you can buy a marimo moss ball and place it in front of the filter.

Creating A Filter Baffle

You can also create a filter baffle if you have the right type of filter.

Making a filter baffle is incredibly easy if you have a cascading filter. All you’re going to need is an empty plastic bottle.

Take these steps to make a filter baffle:

  • Place your plastic bottle next to the filter output and measure how long it is.
  • Cut the plastic bottle in half until it matches the filter length.
  • Wash the bottle thoroughly and remove any chemicals that may be on it.
  • Attach the outside of the bottle to your filter to reduce the strong current.

Use the Flow Control Knob

Filters often have a flow control knob that can restrict water flow and reduce its productivity. This will reduce the water quantity flowing through the filter, water circulation, and strong water currents.

What Will Happen If You Don’t Fix The Strong Current?

Some fish can survive a strong current, and others can’t. If your aquarium filter current is too strong, it can have negative consequences for fish. Here’s how strong currents may affect your fish:


The inability to swim freely in a strong aquarium current can stress your fish. Stress can have negative effects on their health and appearance. It can weaken their immune system and make them vulnerable to disease.

Tire Fish Out

Constantly fighting against the strong filter current will tire your fish. They may struggle to reach the top of the tank. Fish can breathe in the water, but not coming to the surface can damage their labyrinth organ.

See also  Why are my Platies Hiding?

Trouble Eating

If your fish can’t reach the top of the tank, they will have trouble eating food in the future. A strong current can push away the food as your fish struggles to stay on the surface. It will make your fish hungry and also cause food decay in the tank.

Damaging Fish Fins

Strong aquarium filter current can damage fish fins. They might put extra pressure to fight off the current and end up damaging their fins. Plus, your fish might get stuck in the decorations because of strong water flow. 

How To Tell If Your Aquarium Filter Is Too Strong?

Make sure you’re not imaging things before you start making changes to your tank. Fish may become stressed because of unnecessary water flow changes. Here are the most common indicators to determine if the acquire filter current is too strong:

Difficulty Swimming

You should check if your fish are swimming with ease. When the current in your aquarium is too strong, your fish may struggle to swim, and you’ll notice them getting pushed around by the water flow.

Fish Swimming Erratically

Fish should always swim straight. If your fish swims at an angle, it could be because of the strong current.

Keep in mind that some diseases can also make fish swim erratically. Check if your fish is suffering from illnesses such as bladder disease, dropsy, or constipation.

Avoiding The Current

You may also notice that your fish will constantly avoid the strong current area. Sometimes fish stay in one spot because they struggle swimming near the strong current.

Constantly Hiding

Your fish may constantly hide behind the decorations in your tank. If you have a cave structure or plastic plants, your fish may hide in them to avoid strong water flow. These decorations break the current flow and stop your fish from struggling.

Importance of Steady Water Flow

Water flow inside an aquarium is important for different reasons. Here are the main ones:

  • Circulating water ensures the water temperature remains steady throughout the entire aquarium. Water must flow across the aquarium to transfer heat into the water. The filter’s flow dispels the warm water to all corners of the aquarium.
  • The surface agitation created by the water filter increases oxygen transfer into the water. The oxygenated water keeps fish and invertebrates active and healthy.
  • The beneficial bacteria also need steady water flow to remain active and keep nitrite and ammonia levels minimum.
  • Many fish enjoy swimming through and against steady currents.

Choosing the Proper Filter Current and Flow Rate

A proper flow rate and current are essential for your aquarium’s inhabitants. This means that your aquarium will provide a healthier environment for your fish.

A reef tank requires a faster flow rate and a stronger filter current. If you have a 30-gallon fish tank, you need a filter with flow rates of around 120 gph (gallons per hour).

Aquariums that need higher flow rates and stronger currents include:

  • Aquariums with large fish. These need higher flow rates, stronger currents, and additional power-heads to get as much fish detritus into the filter as possible for quick removal.
  • Reef tanks need higher flow to circulate water in all areas of the aquarium. This is also essential for filter feeders.
See also  My Oscar Fish Is Not Eating Food - What to Do?

A planted tank requires a slower flow rate and current.

The following tanks types do better with slower flow rate and water current:

  • Live plant tanks. Decreasing surface agitation helps retain CO2 for plants. Most plants cannot tolerate being in the middle of a strong current stream.
  • Small fish, baby fish, and betta tanks need a slow flow rate. It can cause unwanted stress for fish to swim in the strong current.

Listed Flow Rates

Flow rates listed on the filter pumps are for optimal conditions. But often, conditions are not ideal. For instance, most aquarium water levels are four feet off the floor. Canister filters, modules, and filters need a pump to push the water upward. High-pressure pumps create stronger currents, but high flow, low-pressure pumps can drop their flow rate significantly to cover four feet.

Consider that every sharp turn in tubing slows the flow rate and reduces filter current. Plus, smaller tubing dirty or clogged filters can also have a significant effect on flow rates. If you want to reduce filter current, you can try adding more turns and use smaller tubing.

Another factor in flow rates and filter currents is to consider filter media type. Biological and chemical media work better to maintain a steady flow rate. On the other hand, mechanical media performs optimally with a higher flow rate. Maintain a good balance between the two to achieve a steady flow rate.

The proper flow rate can make a huge difference in the health and happiness of your aquarium inhabitants. Let your fish enjoy a steady filter current by maintaining optimal water flow!

Frequently Asked Questions

What is the ideal water flow for an aquarium? 

It depends on your particular aquarium. An Amazonian river aquarium containing cardinal or neon tetras can thrive with turbulent water flow. If your fish are struggling to stay in one place, then the water flow is too strong.

A strong current in an aquarium can push the plants away and make them lean over. This may look unnatural for sword plants. Plus, some fish like discus, goldfish, and fancy guppies prefer calmer waters.

Do neon tetras prefer strong current?

Yes. Tetras come from rivers with strong currents and prefer strong water flow in an aquarium.

Do guppies prefer a strong current?

Guppies do not prefer a strong current. They are most comfortable in the mild water current.

Can fish sleep without the filter on?

No. fish always need the filter on. If you switch off the filter, you risk increasing nitrites and ammonia.

Does water current speed affect fish’s feeding ability?

Current speeds can affect your fish’s ability to feed. Slow-moving or floating fish do not have the energy and exertion necessary to chase the food you provide through the surface of a strong current. If your current is too fast, the lesser aggressive fish will miss out on necessary nourishment.

The use of extra energy and lack of nutrition can make the fish susceptible to disease. Reducing the current speed in your aquarium is the best solution. It helps maintain a healthy environment for less aggressive aquatic life.

Photo of author

Nadine Oraby

My name is Nadine; I am a passionate writer and a pet lover. People usually call me by the nickname “Joy” because they think that I am a positive and joyful person who is a child at heart. My love for animals triggered me to create this blog. Articles are written by vets, pet experts, and me. Thanks for visiting. Your friend, Nadine!

Leave a Comment