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The chemical metering pump is the heart of a water treatment system.  In order to have proper circulation, the pump needs to be maintained.  Regular pump maintenance is as important as diet and exercise for the human heart and circulatory system. Remember, maintenance is simple to do.  It’s also easy not to do.

Although specific to Neptune Diaphragm Metering Pumps, this checklist may apply to most metering pumps you are currently using.  The 500-series pump design has been manufactured for over 30 years.  Thousands of them in service today.  When properly maintained, these pumps will provide reliable service for 20 years or more.

Regular Pump Maintenance Schedule 


  • Check the oil level.
  • Check for leaks.
  • Check ground connection for corrosion.
  • Clean pump surfaces and surrounding for dust and debris.

First 250 hours

  • Change the oil.

Six-Month / 4000-hours

  • Change the oil.
  • Clean inlet piping strainer.
  • Check external pressure relief valve.
  • Replace worm shaft oil seal.
  • Tighten all fasteners
  • If applicable, check and replace coupling inserts.


  • Clean check valves and replace o-rings.
  • Replace diaphragm.
  • If applicable, replace coupling insert, bearings, check valves.

Here are some of Tim’s videos that are good review when changing parts.  Please call with any specific questions.

Valve Maintenance Video

Diaphragm Replacement Video


Spare Parts

Even though most parts are in stock and can be shipped within a few days, we recommend that you have a parts kit, diaphragm and gear oil on the shelf.  Here is a basic list Neptune 500 Pump maintenance items.  More can be found in the instruction manual.