Just a heads up for use in emergencies etc. Lots of pumps today use ceramic shafts, and they are fragile. Most times yu can get a replacement shaft, but sometimes it may take awhile. This time frame may not be too mujch of an issue with say a skimmer but on a main pump it could get to be an issue. The ceramic shaft can easily be replaced with a stainless steel rod on a temporary basis. Its not gong to corrode up that quick and will not hurt a thing. Stainless is what wsa used prior to them going to ceramic shafts. It matters not what alloy welding rod is used, as even the worst monst unsuitbale stainless steel rod will tanke many months until it becomes corroded. I have pulled lots of pumps and power heads apart and find that either the 3/32 or 1/8" or 5/32 rods will cover most all pumps used out there thats commonly found in use. Odds are a welding shop or supplier will give you one for free. They are normally 36 inches long. Some places will even have titanium rods and then there is always carbide electrodes as well. So there really is no need to get behind the 8 ball from a simple pump shaft getting broken. SImply cut it to length and install just like it wa a genuine replacement shaft. Even if that temporary stainless steel shaft is slightly undersize in diameter the pump will still work, just fine.
I have the capability to grind ceramic myself so making a replacement shaft is not a big deal. YOu can buy all sort os shapes ands sizes of preformed ceramics to machine grind what yu need, but snipping off a piiece of stainless steel welding rod is certianly much quicker and easier until I get time to make a proper ceramic one. I have done it for myself as well as others quite a few times and the local LFS here sometimes gets kind of heavy handed when they clean their pumps, so now they too keep a few stainless steel rods around for those emergency uses.