Last weekend, while clean up my skimmer SRO-XP-5000int, I noticed the imperller of the pump HY-5000S wear unevenly. The white cylinder part is a little off, after I put it back all together I notice loude noise when pump in action. The replacement Impeller is ROP-BB5000-IMP $98.99. Why it so much more expensive compare to the impeller of the Varios-6S DC pump? The HY-5000s pump is $280 but the impeller is for $99, while the VarioS-S6 for $339 and the impeller for only $36. Im still debate between buying the impeller or buying the whole pump. Also which is the best fit pin wheel pump for the SRO-XP-5000int between the RC-DC5500, VarioS-S6 or the legendary HY-5000S? Thx