Replacing Single Speed Pump with Variable speed pump - Have Hayward S240 Sand Filter


New member
Mar 26, 2021
I'm getting ready to replace my Single speed pump with a variable speed pump. The new pumps have a higher HP so I'm concerned I'll blow the sand out of my Hayward S240 filter when I backwash so I'm trying to locate a manual for the S240 so see what the recommended S240 flowrate is for backwashing. The plate on the S240 says 20 GPM but that seems pretty low. I've seen a couple threads looking for the manual so I'm hoping somebody has it.



Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Welcome to the forum!
A VS pump is a Variable HP pump. Just use a lower rpm (like 2000 rpm) for backwash and see if that is high enough to clean the sand and low enough to not get too crazy.
I suggest you read ABC's of Pool Water Chemistry.
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