I had an open loop installed last summer and should have chosen closed loop. I picked the open because of the increased efficiency and lower initial cost. I used my existing domestic well (25 gpm) and had tests done to confirm the water quality was good. I had changed my whole house filter about every 4/5 monthes prior to the Geo but now I have to change it every 5 days because it clogs up. I have clay problems like I never had before I guess due to the massive increased water use. I checked around for a backflushable filter system but nobody will touch it. So I have now decided to convert to a Closed Loop. My installer says my 4 ton unit should have 4 - 150' holes. I was thinking about 2 - 300' or even 1 - 600 foot hole instead. It just makes sense to me that there would then be less connections buried underground that could be potential future problems. I have asked around and nobody can give me a definitive answer what is best. Any help would be appreciated.