This was a tough week for a fellow in Hendersonville North Carolina.
Clyde Halbert had spent years building up his fish stock and estimated he’d invested nearly $40,000 in purchasing catfish for his pond.
Halbert operates a business where folks can come in and fish for trophy sized catfish. They pay him a small fee, and can then fish the pond and try to reel in some cats weighing up to 90 pounds. The operation is completely catch and release so the fish go back and do what fish do. Relax, scrounge around, maybe fool around a little bit, and eat more to get bigger.
It’s not a bad life.
Unless you run out of air that is.
Halbert’s pond is about 3.5 acres in size and he has very good depth. Something in the area of 17 feet in most of the pond. And he had two fairly large fountains running full on, and although they were helpful, they simply weren’t enough to stop an inversion once it began.
In case you’ve never heard of a pond inversion, in simple terms, it’s when the pond literally turns over. Warmer water is found on top, and cooler water is near the bottom. And on occasion when conditions are right, such as a heavy downpour of rain or really high winds, these separated thermal layers in the pond switch places.
This causes a major disruption in the pond and it can stir up a tremendous amount of muck and gunk found on the bottom. At times, when this happens, trapped gasses can escape from the muck in mass, and a lot of other unwanted things are stirred up in the water column. The end result can be a rapid drop in dissolved oxygen levels and we all know what this can mean.
As in the case of the catfish pond, many of the largest fish were affected first since their oxygen demand was greater. But it’s also not uncommon in cases of inversion to lose everything.
And the end result in Halbert’s case was to remove and dispose of an estimated 1200 fish, some in the 70 to 90 pound range. As you might imagine it was not an easy clean up process, nor was it pleasant.
So Why Didn’t The Pond Fountains Protect Against This?
To be truthful, the fountains in the pond were helping somewhat in adding oxygen to the pond. They helped to disrupt the surface tension of the water and in that way they aerated things a bit. But like most fountains, their positive affects simply didn’t go deep enough.
So much of the important work in a pond actually happens at the bottom, and not the top. Beneficial bacteria must have good oxygen levels in order to break down muck and sludge and keep it from building up. And often by reducing or limiting muck and sludge you can highly limit the chances of an inversion happening in the first place.
Along with that, in ponds with no bottom aeration, or just fountains running, you’ll find that thermal layers form where the top of the pond will be a good bit warmer than the bottom. When you aerate with a sub-surface system, these separated layers go away, and temperatures and dissolved oxygen become more consistent throughout the pond.
All this is extremely healthy and protective and this particular story is a prime example of why we almost always suggest looking at bottom based aeration first over a fountain in most ponds.
Fountains are great additions to ponds, and they add a wonderful ambiance that is really hard to beat. But it needs to always be kept in mind that they may not be enough when it comes to adding good levels of oxygen throughout the entire pond.