This small gadget I would never be without and they aren’t well known. One of the most important purposes of an aquarium is movement and therefore also oxygen supply. While air stones are largely decorative they can have a purpose in helping oxygen saturation by breaking up the surface of the water. Many filters do not provide enough of this surface movement and this is where venturi’s come in.

Venturi’s are a solution to this, they simply use the force of the filter outlet to pull air through into the water column. The amount of flow provided is much stronger then without or with a spray bar. So while this might not be much use for fishes such as Betta splendens that like next to no current for most fishes particularly those that like a current it is really a life saver. On top of these benefits it helps you identify the route of flow through the tank from these bubbles.

These little adaptations are easy to setup, all that is required is hose line that can attach it to the external filters outlet, I recommend heating that tubing with boiled water for 10 seconds to make it easier to attach.

There are are few available on the market and some filters come up with attachments that force air through. I have trialed a few over time but the majority tend to be loud or produce little air. Eheim’s remain the only you could attach to any external filter with a spare bit of tubing. There are some cheaper ones on the market that attach to filters I cannot comment on.

Most of my comments on these are through experience. I keep largely high flow fishes and one powerhead wouldn’t cut it. Since adding these I wouldn’t look back, improving flow but also oxygen saturation and where these fishes also need higher temperatures oxygen saturation is a limitation. For around £7-10 it’s not much more, while designed for Eheim filters they should work on Fluval and other brands.

One big question would be do they reduce the flow of the outlet by creating a barrier? It seems very clearly not. My only worry is back pressure on the impeller and filter pump but in maybe 4 years of having them I’ve had no issues with them.

Otherwise I cannot recommend this simple device even more. They change aquariums for the better in many ways.