How to Reduce Filter Current in Aquarium

Water flow throughout your aquarium is a good thing. But, sometimes, the outflow from your filter causes currents too strong.

This can be especially annoying if you’re trying to grow floating plants in your tank, or if the strong current is washing away flake food before your fish have a chance to eat it.

Here are some ways to help reduce filter current.

Adjust the Outflow

Seachem tidal filter on aquarium

Just in case you missed it, double check your filter for a flow control lever.

Most hang-on-the-back filters have a little lever that lets you reduce the outflow.

Canister filters usually don’t have this feature, but you can check the user manual for your model of filter, just in case.

DIY Baffle

A baffle is a barrier that slows the water down as it comes out of the filter.

Plastic Water Bottle Baffle

This kind of baffle really only works on smaller hang-on-the-back filters, but it is a really simple solution. 

You just need a marker, sturdy scissors and a plastic water bottle.

Steps: 

  1. Cut the bottom and the top of the water bottle off with the scissors so that you’re just left with a cylinder. 
  2. Cut along the long side of the cylinder, splitting the side completely.
  3. Put the cylinder up against the outflow of the filter and use the marker to mark how wide the outflow is. Then trim down the cylinder until it is just a little bit shorter than the outflow is wide.
  4. Pull apart the split side of the cylinder and place it over the filter outflow. The cylinder should hold itself in place, while also creating a barrier that slows down the water flowing out of the filter

Sponge Baffle

Creating a sponge baffle is another option. The best kind of sponge to do this with is matten filter sponge pads. They’re sheets of coarse sponge material that you can cut to the size you need.

For a sponge baffle, you’ll need a sheet of matten filter sponge and a sturdy pair of scissors.

Steps: 

  1. Cut a strip of matten sponge that is about a ½ inch (1.25 centimeters) wider than the outflow on your filter. Leave the strip as long as possible, you’ll trim it off later.
  2. Push this strip of sponge into the outflow and as far as it will easily go.
  3. Trim off any sponge that is hanging out farther than the lip of the outflow.

This piece of matten sponge will slow down the flow coming out of the filter, and it will provide extra surface area for beneficial bacteria in your filter, but it will also need to be rinsed out with dechlorinated water from time to time to get rid of built up gunk.

I’ve had good luck using this brand of matten sponge in the past.

Hipanda Filter Foam Sponges, Durable, Bio Sponge Filter Media Pad, Cut-to-Size Foam for Aquarium Fish Tank (9' x 9' x 1' (2cs))
Hipanda Filter Foam Sponges, Durable, Bio Sponge Filter Media Pad, Cut-to-Size Foam for Aquarium Fish Tank (9" x 9" x 1" (2cs))

    Last update on 2024-03-04 / Commissions Earned / Images from Amazon Product Advertising API

    Pre-made Baffle

    There are also some pre-made baffles available on the market. 

    These are floating barriers that you suction cup to the side of the tank. The suction cups hold brackets that let the barriers move up and down as the water level changes. 

    I like this style of baffle particularly for cutting down the flow from the filter so that floating plants don’t get bounced around the tank.

    HOZOE Aquarium Floating Plant Corral, Intercepting Floating Plants from Filters and Heaters, Adjustable Height with Water Level, Can Be Used to Framed and Frameless Aquariums. (Combo Pack).
    HOZOE Aquarium Floating Plant Corral, Intercepting Floating Plants from Filters and Heaters, Adjustable Height with Water Level, Can Be Used to Framed and Frameless Aquariums. (Combo Pack).

      Last update on 2024-03-04 / Commissions Earned / Images from Amazon Product Advertising API

      Decor

      Using a baffle isn’t your only choice when it comes to slowing down the outflow from your filter.

      You can also place pieces of decor in front of your filter to slow down the water rushing from the outflow. 

      Rocks, driftwood, resin decor, even tall artificial plants can help lessen the flow coming from the filter.

      Final Thoughts

      Water movement in your tank is great, but sometimes, you can have too much of a good thing.

      Always check for a lever to cut down the flow on your filter first. You may have a really simple solution right in front of you.

      If that’s still not enough, putting things like rocks or driftwood in front of the outflow can help to break up the stream and slow things down.

      Baffles, whether you purchase one or make a DIY one, are another good choice for reducing filter current.

      I hope you find this article helpful.

      I wish you and your fish the very best!

      Katherine Morgan
      Katherine Morgan

      Hey, there! I'm Katherine from Northwest Florida. An aquarium specialist, I've kept tanks for over two decades, enjoy experimenting with low-tech planted setups and an avid South American cichlid enthusiast.

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