noble, If your pond is 2 acres in size and you have a 1.5 CFM output windmill consider putting the airstone (Im assuming it is a 7 inch Koender stone)inapprx 4 ft of water off to the side approx 20 ft from shore and let it fly. If thin ice in a small area is not a problem this is a better idea then investing in a DO meter. With your current aeration system you may have more of a DO problem in the summer than in the winter.Ted
