I have a pond that has been in place since 1996 stocked with Bass and Bluegill. With an open loop system the water does get circulated around (to some degree)and I do see bubbles from the geothermal return line. The fish have been in place for nearly 20 yrs and have survived. However, the reason for my question is I have lost just enough fish to make me wonder if aeration is necessary. In all I would say I have lost 20 or so bluegill and 3 smaller largemouth this year. All signs point to oxygen depletion: Carp lapping at top of water and fish being lost early in the AM and being found in the morning. My concern is will an aerator pump kill the efficiency of the geothermal and/or cause things to get stirred up and stuck in the intake? Any advice from others with an open loop system would be greatly appreciated. I have owned the property for a little over a year.

How large is the pond?

I have open loop in my .62 acre pond and it's never been an issue. The loop discharges about 20 rpm max at intervals but doesn't last very long. Not enough to be a problem.

I know this because I've observed it when refilling the pond and the water line that is lashed to a stake was above the water. Just looks like someone turned on a garden hose and then turned it back off.

Edit:

I see now it's half an acre from another thread. IMHO the discharge should not be an issue whatsoever. You may have somewhere around a million gallons depending on your depth so that little water won't make a difference. And it will pick up oxygen through diffusion.

My first thoughts were that it was like my system -- but mine is closed loop. My loop pipes are filled with about a 15% alcohol-distilled water mixture. I was first thinking that maybe the alcohol was leaking from your system.

Mine is a Water Furnace Envision-Series, which is what I think Cecil also has.

However, I am curious about how your open loop systems work. We put in a closed loop system several years ago that uses two 300-foot "wells" fitted with up-down 2-inch flexible black PVC pipe. The pipes leave and enter my basement about 7-feet below ground level, to and from the wells. The output pipe goes out to the first well, goes down about 300 feet, comes back up to about 8' feet below ground level and goes to the next well about 15-20 feet away, where it goes down 300 feet and back up and into my basement where about 7-feet below ground level. We can get up to about 3-feet of frost here.

Anyway, with an open system, how to you keep debris from entering the pipes? Do you have to be concerned about the incoming water freezing between the pond and the house, or are your lines buried well below the frost line?

Ken

Ken,

After 21 years we replaced our water furnace with a Bard that is also a larger system. More efficient and a more modern system. Has also cut our utility bill in half.

No freezing as the discharge line is quite deep under ground. And I also have it staked under water several feet down to keep it out of the ice in winter.

As far as anything getting in It would have to swim upstream against the flow at least 200 feet. I've seen algae on the discharge pipe under water, and even some iron/calcium deposit encrusted on the end, but when I cut a couple inches of the plastic pipe off it was clear.

FWIW We have a "pump and dump" (open loop) in our pond. I have seen no issues with running aeration. We don't use it for heating as the cost of electricity in our area is very high compared to natural gas. We have a 98% efficient gas furnace (GFA) for heat and use the geo for cooling only. The problem with heating with our geo is when you compare the cost of electricity of running the well pump, the geo unit and the furnace blower for much longer run time than the GFA required short run time, we save $100 a month by just heating with the GFA furnace. For cooling, the numbers work much better and geo is a cost savings for us. So is geo cheaper?....IMHO well "it depends" on the cost of electricity vs natural gas in your area.