I have no idea how well a sponge filter would work for goldies, but if you have 2 filters in there, I would suggest one regular filter, and a sponge filter. I use the http://www.petsmart.com/product/inde...ductId=2753029
which is what you have... How come it is bugging you? is it just the size that is making it vibrate more? Use a 40 gallon pump maybe, (if that doesn't work I want it :p hehe). I have the 20 gallon one. And it doesn't make a single sound. I use it for 10-20 gallon though. If you DO have another filter meant for a larger tank you can get away with it.
Be warned though, you will want to get a 70 :3 those fellas are pooping machines :p plus get to a decent size <3
Then get the sponge filter pieces, or jsut an aquarium sponge you can anchor to the bottom with weights or rocks. Getting tubing, and an adjustable valve for air flow. Cleaning is as easy as take out, rinse in old aquarium water, put back
If you want go with Fluval (three sizes on petsmart http://www.petsmart.com/product/inde...ductId=4455062
- you can see the one review saying it is better than aqua clear xD
Here is one I use! http://www.petsmart.com/product/inde...ductId=3943444
I love it. Generally quiet. the water level goes down, it doesn't make a churning sound that says "FILL THE WATER UP!" it stays quiet. If it still has the water high enough, it's just dribbling water for sound. I will recommend this 100%
PLUS adjustable flow, easy to clean, etc.