Thanks, Cecil. I'll look forward to your response, when you get time.
I actually have been running the diffusers at night during the summer. I have them on an electronic timer. But the bottom water temps still climb to the mid 70s.
Oh I see. Then you definitely need well flow to cool things down. The question is how much do you need? And can you get by by feeding it into the bottom of your pond without the use of diffusers instead of trying to cool down the entire water column?
The only other alternative is to dig a smaller pond upstream for your trout that is easier to cool and make your present pond a "coolwater pond" that receives flow from the trout pond with smallmouth or all female yellow perch or something like that.
Personally if it was me I'd go the latter route. Lots cheaper than trying to pump up lots of ground water unless you have a high static well water level. If that were the case you could use a surface pump to get a good flow out with much less power than a submersible well pump.
