What Maintenance Is Involved With Rocking Piston Aeration Pumps?

Mark Washburn

There are several types of pumps used with pond aerators these days.  For large ponds, you'll find systems powered by rotary vane or rocking piston pumps, and by a pretty wide margin, rocking pistons are finding the most use.

With that in mind, we get a lot of questions relating to maintenance on this type of aerator pump and so I wanted to address that briefly here.  And don't worry, nothing will be very complicated or complex.

There really are two main things you need to keep an eye on with rocking pistons.  

Air Filters

The first, and this really goes for any pump in general, is the air filter.  The quality of the air output, will be directly related to the quality of the air input...and the intake air filter has a big influence on that.

Most of our current line of aerators use a filter cartridge that is simply removed from it's housing and replaced with a fresh one.  Now how often you need to do this will vary a lot based on the environment the pump is in.  If it's a pretty dusty area, you may want to replace these every few months.  A cleaner environment might allow you to go 6 months to a full year before replacement.  Mainly you want to just keep an eye on this filter and when it gets some build up on it, replace it.  The cost per filter cartridge is under 10 bucks.

By far, the filter will be the most frequent maintenance item on your "to-do" list.

Piston Gaskets And Seals

The other main maintenance on this type of pump will involve replacement of the gaskets and rubber seals on the piston and piston chamber.  This sounds more complicated than it actually is, and in 99% of the cases, the pond owner will do this update on site with a few simple tools, and about 20 - 30 minutes of time.

Basically, this pump is designed to run continuously...24/7, 365 days a year, if you want it to.  Over time though the rubber seals on the piston will begin to wear down and as they do, you'll start to notice some compression loss and lower output of air.

In a single diffuser system, you may notice less bubbling coming out of the diffuser, or the bubbling will stop all together, yet the pump will continue to run.  With multiple diffusers it's common to see air output out of one of the locations, while the others may look fine.  People sometimes confuse this with a blocked diffuser or airline, but that kind of thing is generally pretty rare...so the first thought should be to consider the seals on the piston.

The time frame leading up to this issue can vary a lot.  Some of the variance is related to the pump itself (brand, horse power, etc) and some of it is related to the installation dynamics, such as depth of the diffusers, length of airline runs, and so forth.

I usually expect to see around 2 to 5 years of continuous operation of a pump before the seals may need to be replaced, but in some challenging situations, you may need to update these yearly (all should last at least a year).  On the positive side, we've seen some of these pumps run from 7 to 10 years before needing anything...although that might be the exception to to the rule.  Most often I suggest simply running them until you see an air output drop, then replace the seals.

All manufacturers offer kits that included all the components to update this part of the pump.  Prices vary by brand and by horsepower of the pump.

Final Suggestions

So that's really all that's involved in maintaining the rocking piston aerator pump.  They are one of the most reliable, powerful, and efficient continuous duty pumps you'll find on the market today.  They often can handle very challenging depths (some up to 50') and run multiple diffuser systems very nicely.

All of these pumps require some kind of weather protection...meaning you want to keep them dry.  They will also heat up during operation.  So much so that you wouldn't want to touch them...and this is normal.  But because of this they do benefit greatly from good ventilation and air flow over them...which is why all of our protective cabinets include cooling fans in them.

It's not a problem to make your own enclosure, or put them in some kind of shed, for example, but they need to be kept dry and as cool as possible.  If in doubt, consider one of the factory cabinets that we offer in the systems....we've never had an overheating problem with one of those.

Finally, do the best you can to keep the pump in a fairly clean and dust free environment.  This isn't always possible, but the cleaner you can keep the pump, the longer and more reliably it will run, and your maintenance issues will be kept to a minimum too.