Need suggestions for a good, quiet replacement pump for skimmer

my old sedra 3500 was very quiet and my sedra 5000 i have now is very very quiet. its on a euroreef recirculating skimmer

 

Is it the air being sucked in that is making the noise or the pump itself? If it is the air, can you put a silencer on the air intake? If it's the pump, have you tried cleaning it? Sounds like the cord is bad anyway. I have a eheim 1262 0n my skimmer. Very efficient and quiet. Has a mesh wheel.

 

+1 on the sucking air noise. That won't matter which pump you use and is actually a good sign since the more more (in general) the better a skimmer works. Get or build a silencer for the sucking noise. They usually come with them so I am assume you bought this used.
If your skimmer was working well, like an ASM definitely can work, then I wouldn't change the size of pump. They are matched to the performance of the skimmer. Also, the Sedra is considered a good pump although you have ahd you troubles.
Eheim is a GREAT pump, but if you change make sure to match the flow rate as close as possible. But beware it may not work as well, but it could also work better. ;0)

 

Get a 1" - 1 1/2" piece of PVC about 6" long and two PVC Caps. Drill a hole in each cap the size of your air line and put the caps on each end and insert the airline in one end. Silencio!