Thanks for the advise on the over pressure pop off I like that. I still have my initial question, how much air do I need to turn over this little pond. The system I am trying to design is multi purpose and will allow for a lot of operator control might be complicated in theory but has some tangible benefits. I spoke with a fella who rebuilds the Gast pumps and he said two years is the average life span, and two hundred dollars gets you back on the road. I am hoping to do better than that. Thank you for your advise I will get some better diffusers and use my existing pump. When it all fails again I will have the information to experiment with my design.