Marti8a,

I work in the pond industry very close to the company that produces the centipede and I would not say that the Centipede and snorkel is expensive. That would be putting it too mildly. They run in price from $400.00 to $1300.00. I suggest that you go to the following website "http://www.bogfiltration.com/";. It will tell you a very simple way to make your own at very low cost. It will cost you less than a $100.00 and will work better than a Centipede and snorkel.
Mike

Thanks Mike, that looks really interesting. I'm not sure our upper pond is big enough. It's only 7' diameter and 4' deep.