frothy bubbles???

This is caused by bubbles being to fine and not bursting on the surface as they should. Sometimes after addign water conditioner this can happen to. Do you have a valve on your air line that adjusts the flow of bubbles? If so and you don't like the bubbles on the surface like that, just open it up some more. If not then you may need an air pump that can put out more air. Also if you are using a new bubble stone it needs to soak in the water for a little while before it will start to put out good bubbles. There is a type out there that is made out of something that resembles cardboard, I have no experience using these so I cannot say what you can do to fix it if you are using one of these. Hope this is helpful!