[bostoneric]

Air stone for sure, but if you are adding air to the setup take advantage of it and add a air powered sponge filter. It will really up your shrimp game!

I think any if the typical brands are about the same noise level. There are a few tricks you can use to help dampen the vibration noise. I've seen people place them on top of a soft sponge, different things like that.

 

[Raymond S.]

As long as the body of it doesn't touch anything but only the legs sitting down on whereever you put it, a Wisper is about as quiet as I've ever seen(heard)/had.
Before you buy one, find a site that has the repair kits. I'm not an engineer but if one has the same identical repair kit as another model # one does, wouldn't that make you think that they can't pump any different amount of air ? A couple of the models do have the same repair kits.

 

[jrman83]

Do you monitor your CO2 at all? Drop checker, ph monitor? Sounds like you have it turned up too high. You can have good surface movement and CO2. I wouldn't run an air stone at the same time I was running CO2, but doing so once it was off would be okay. Personally don't think you need to add any more equipment to fix what sounds like an adjustment error.