Problems with wet/dry filter

I was wondering if anyone could tell me why my wet/dry filter is spitting out micro-bubbles about every 5 to 10 seconds. The water level in it is fine and it is covering the return pump and the flow back to the tank seems fine, but for some reason it is still spitting out micro-bubbles. I have the overflow box dropped down to about as far as it can go beneath the water surface in the main tank and the water level in the main tank is at max itself.

Thanks for the help,

Bradd

I am using the Pro Clear Aquatics Pro Series 75 wet/dry. Is there a way to use a Tee fitting with it? The only place I see that I can add a Tee fitting to this wet/dry is where the water comes into the wet/dry via the overflow box.
I am not sure what you mean by placing the Tee fitting in before the pump...my pump sits in a section all of it's own. With this wet/dry the water comes into a large chamber, flows into the top of the filter, drains through the bio balls, goes through a sponge filter into the compartment where the pump sits, out the pump and then back into the main tank.
Any help would be appreciated.

Thanks,

Bradd

I called tech support and found out how to fix this. If anyone is using the pro clear aquatics wet/dry filter and having a problem with micro bubbles in their tank here is the solution:

Take the sponge filter that is underneath the bio balls and move it so it is about 1/4 of the way into the section where the return pump is situated and then press down on the sponge so that there is water totally flowing through the sponge. That is all there is to it. After talking with tech support I tried this and it has worked great for me. Of course, I am using the 75 Pro Series so it might be different for the other wet/dry filters made by the company but it has worked great for this one.
Hope this helps anyone else with this problem,

Bradd