I took out the plug and ran tubing to the intake on my powerhead.
I put tubing into the hole that you can use for air injection. It pulls water constantly through the diffuser and works aweome !
25ppm in my 30 gallon... plants are growin like weeds and my fish are healthier then ever.
And mind you this tank is WAY overstocked by conventional terms. I have not been over 1ppm on ammonia(tested daily)
I had all these fish in a 56 gallon that I had to break down and move for carpeting...
Here is a photo of diffuser in tank... line out the right goes to powerhead