Lee,DEPENDS > on the depth of your pond 20 psi might be OK might not,I hope the system in 7.5 CFM as 2 or 3 stones will require that and you still will only get about 50% of the water "turnover" of a Vertex Airstation. If you are interested in a diffuser that will perform at 1CFM look at the vertexwaterfeature.com web page. Fill out the questionaire and get a system that is the most efficient on the market.I have the Great Lakes ALA-4GL airstone set up beside a Vertex Coactive Airstation in one of out display ponds and pump 1 CFM to both and the difference is amazing. That airstone only produces 1250 GPM turnover at 12 ft depth compared to the Vertex diffuser at 2778 GPM turnover.I hate to sound like a commercial but these are the facts.(and some of the reasons I am a distrubutor for Vertex)