The March Pump is a nice pump. Magnet couple, no contamination, poly sulfone pump head but it also has it's "issues" Can't self prime, low flow, low Delta P, jams up easily when trub hops etc get in the way.
The Little Giant 3-MD-HC is an excellent high temp high corrosive pump producing maybe two or three times the flow and Delta P of the March and holds it's prime against a lot more interference than the March. And yes, you can pump boiling wort through it all day long.
The LG pump has a flaw though, but one that is easily remedied.
In the center of the pump head is a little ceramic shaft. On that shaft the factory has put a black Moly Lube. The function of the shaft is to keep the pump head rotor in the center of the magnet coupling field. Ceramic is an abrasive material. They used Ceramic because the pumps are rated for HIGH CORROSIVE.
Unless you like the idea of drinking black moly lube you gotta do something about that.
The options are:
1.) Edible Food Grade Lube. Yes it exists. There are a whole slew of "food grade" lubes out there, but you need one that is classified as edible and food grade does not mean edible. Such lubes don't last so you'll need to get a cartridge or jar of the stuff and refresh the lube each brew day. This is no sweat 'cause the LG pumps are the sweetest things on earth to open up. unscrew 4 little SST wing-nuts and you are inside the pump.
or
2.) Replace that little ceramic shaft with 1/4" teflon (or Rulon 641 if you can find it) shafting which you can get cheap on the Flea Bay and file the ends with little flats like the ceramic shaft. Easy peasy take you all of maybe 10 minutes or less.
or
3.) If you have a friend with a ceramic kiln, you might apply a nice pure white or clear ceramic glaze (glass paint) to the factory ceramic shafts ( after soaking for a very long time in 111 Trichloroethane to strip away all the lube and then dry firing them to burn off anything you didn't get out) and fire it to fuse the glaze into a nice slick coating.
