Best way to add air without adding too much turbulence?

I have 7 ember tetras in a 20 gallon long planted tank at the moment. I've switched to a smaller airstone, but they still avoid most of the tank and only want to be near the front. On one hand, it's great because I get to watch them, but on the other, I worked hard on the rest and miss out on watching them explore. I'm worried it's because the airstone is too strong or the noise is too loud. Is there a way to make smaller bubbles, or an airstone you recommend?
The filter is already muffled with a sponge, which seems to help a bit.

 

I have 7 ember tetras in a 20 gallon long planted tank at the moment. I've switched to a smaller airstone, but they still avoid most of the tank and only want to be near the front. On one hand, it's great because I get to watch them, but on the other, I worked hard on the rest and miss out on watching them explore. I'm worried it's because the airstone is too strong or the noise is too loud. Is there a way to make smaller bubbles, or an airstone you recommend?
The filter is already muffled with a sponge, which seems to help a bit.

What about a small sponge filter?

 

I've been thinking about that! I think that's a good idea. Plus, extra filtration never hurts

 

I use a hygger airstone it creates micro bubbles

You can use a small airstone in the sponge filter also if you go that route

 

What kind of filter are you using?

I've never used an airstone and have never had problem with oxygenation. My smaller tanks use HOB filters and my large tank uses a canister filter that I point up to create surface agitation.

 

I run 2 FX6's

 

Air stones merely provide oxygen by agitating the surface. The output from an HOB provides surface agitation as well (especially if you keep the water level an inch or two lower. Adding a powerhead to the tank will also produce oxygen as well as giving the fish exercise.

 

Air stones merely provide oxygen by agitating the surface. The output from an HOB provides surface agitation as well (especially if you keep the water level an inch or two lower. Adding a powerhead to the tank will also produce oxygen as well as giving the fish exercise.

Scientists have known for at least 3 decades that the majority of oxygen from a bubble plume comes from the bubbles themselves. The latest study says it's >95% bubble and <5% surface.

 

I like a few big bubbles rather than a lot of little ones. I use a gang valve to bleed off air to slow things down and bury the air stone to get large bubbles.