Betta-Safe Water Pump Diffuser

Calming the Waters in a Fluval 15

If you've got a Fluval 15 aquarium, this printable diffuser will make it easier for your betta to swim.

30 July 2025

I printed this diffuser with Prusa Galaxy Black PETG. It screws into the pump outlet just like the stock one. I printed this diffuser with Prusa Galaxy Black PETG. It screws into the pump outlet just like the stock one.

Bettas are beautiful fish, but because of their long fins, they are also very weak swimmers. Fast-moving water is hard for them to swim against. I noticed our own betta, Blueberry, was really struggling.

Resources

Let me know if you successfully build this diffuser - I'd love to see it!

I designed and printed this drop-in replacement water diffuser for my Fluval Flex 15 gallon tank. It has a threaded end that matches the stock water pump outlet, so you can just screw it into place. The result is a much more placid tank, without reducing the throughput of the filter pump.

OK, he may be struggling a bit here, but you should have seen him struggle *before* I installed this new diffuser!