Ummm if you don't use wind or electric how do you plan to compress the air?

15 to 20 minutes a few times a day will not be enough to make it worth while. At least I don't think it will. In a pond your size which is about the size of mine you really need your air running I would say at least 4 hours a day to do any good. Lets see what others have to say. I am no expert on air just giving you my 2 cents.

RC

The only difference between a rut and a Grave is the depth. So get up get out of that rut and get moving!! Time to work!!