I have posted this on KoiShack. I figured this might be of interest to those that do the Shack.
While designs for the different brands and models of diaphragm pumps vary some....they are all using the same principle. You have two large electromagnetics (looks like large transformers). Suspended between the electromagnets are two permanent magnets in a plastic frame. The plastic frame has a threaded rod on each end. These threaded rods are inserted into reenforced holes in the diaphragms. So when the the alternating 110V current makes the two eletromagnets change their field direction (ie north pole, south pole) 60 times a second, those permanent magnets react moving one way and then the other. This is what causes the diaphragms to move and act like bellows on a iron forge.
On the outside of the diaphrams are plastic end blocks. The contain the check valves and passages that direct the pumped air in one direction down to the underside of the pump. The check valves, just like the diaphragms, are made from synthetic rubber and definitely wear out. So if you see an air pump running with what looks like 50% output....it could be
one or more ruptured diaphrams (very likely)
or more more broke check valves (very likely)
one or more electromagnets have died (not so likely)
Depending on the brand and model of air pump. your purchase individual replace about parts or kits. Some kits contain a new fiilter. This is really needed...just wash and dry the old one. What you do need to have on hand is at least one set of diaphragms and check valves.
Check out this site...
http://www.septicsolutions.net/store/homepage.htm
Why route you to a supply of septic tank systems? Because a septic tank, just like a koi pond, runs much better when there is plenty of air moving things about. Also look at all the brands they carry. Where did you see such a selection for a pond supply house?
Next go to the parts page:
http://www.septicsolutions.net/store/PumpDifferences.htm
Select a brand and model of pump....lets try one of the HiBlow models
http://www.septicsolutions.net/store/PumpDifferences.htm
Here you can see the end blocks and diaphrams.
On this page you can find Alita parts:
http://www.septicsolutions.net/store/alitalinear.htm
Whe you scroll down....note you can purchase the check valves seperately!!!!
For a Medo linear piston pump:
http://www.septicsolutions.net/store/medoairpump.htm
Clean the filters several times per year. Have spare diaphragms and check valves (or piston kit for Medo) on hand for all the different brands and models you use.
Yes.....some of the check valves and diaphrams just might fit another brand and model as well.
My point is with all this...... keep your air pumps working...your fish depend on them!