Pond Boss Forums INTRO Questions & Observations Moving Aerator in Winter?

Vane replacement can occur less frequently than every 10000 hrs if the compessor does not have to pressurize at 10psi. If the pump runs at 5 psi the vanes will last longer maybe 20,000 hrs. Also dirty air filters hasten vane deterioration.

Some compressors that had Emerson motors had occassional start switch problems, but never any problems with GE motors. Moist operating environment can also be a problem for starting and stopping some compressors esp those poorly housed.
For the last ten years we have not had very much trouble with starting and restarting GAST compressors providing the compressors are maintained and operated properly. Most pondowners are not told about the proper running conditions for the pump. Sellers usually spend a minimal time with the buyer and the buyer leaves nieve about pump care & operation. Often buyers get units from mail order and instrucions for compressor care is almost nonexistant from these sellers.

Shattering of vanes sounds to me like the occurrence of a spike of excessive pressure. This can occur under several certain conditions. This is the only reason we see shattered vanes. It is not due directly to starting and stopping, but maybe indirectly, esp if simple preventative items have not been installed or maintained.

I think that metals & carbon expanding and contracting differently within the compresssor are very likely not the cause of shattered vanes. Was this confirmed by an engineer at GAST?

I'm not sure what you consider temperature extremes for re-stratify. The amount of restratification of the surface layer that can occur in one day is not a big problem, as I have seen it at least in many places in the USA outside hot desert areas. Even in those areas, I doubt it would be a major problem. BOD is the primary cause of oxygen loss in the deep zone and surface sediment areas. To compensate for this possible problem, most of the aeration distributors in my area have pondowners run their units twice a day for 2 to 4 hours each time. Some will run three times a day for various periods or once a day. I can make a convincing argument for doing it either way so it probably doesn't make a lot of difference at least in most ponds in our area of the country -northern midwest. Exceptions can occur (see next paragraph) but they are not the typical or normal pond.

I have tested oxygen loss rate in restratified ponds. It is variable but the pond has to be almost a sewage pond before oxygen at 6 to 8 mg/l (ppm) is consumed down to below 3ppm within 24 hours at the bottom in the restraified zone or newly formed hypolimnion. Another exception would during a plankton bloom crash which causes a bacterial bloom which consumes DO very fast.

Invertebrates will probably be the first to go in the upper sediment when the pond restratifies. Fish will be first "to go" in the pelagic areas when oxygen is depleated from the deep zone. Since aerobic bacteria are fairly low oxygen tolerant they will likely be last to die as the zone turns to anoxic. Anoxic conditons first occur at the mud water interface. In fact with continual aeration 24/7 the bottom is warmed more than if the system were run for a shorter period. With warmer bottom sediments from 24/7 operation the oxygen will be lost quicker at the mud water interface due to greater bacterial/invertebrate activity. However this can be a positive if rapid sediment consumption is a goal.