OK, I see. You have a cartridge filter, not the DE filter. I'll put the correction image below . . . but blocking the #8 "25021-0004 Air Bleed Filter" would have no effect on the flow rate.

Quote Originally Posted by meghanW View Post
So we would just assume that the filters needed to be cleaned. We tested it out and cleaned them and them turned it on and about 5 mins later it said low flow. We have had our filters for about 2 1/2 years and the bands around the filter are coming off. Could that be a sign that they need to be replaced.
Yes. Those System3 cartridge filters are, in my opinion TERRIBLE. I put 3 of them on a commercial pool, in an emergency filter replacement, and very quickly learned to despise them. After 2 years, I converted them to DE filters. Some people like them but it appears that people for whom the work well mostly live in areas where there's little or no pool debris from vegetation and thunderstorms

Here are the parts you need for the S7M120:
large outer cartridge
small inner cartridge
tank O-ring
The large cartridge is currently listed as unavailable from Amazon, but they are probably available from A1-PoolParts, nearly as cheaply:
S7M120 parts
And, here's the Pentair / StaRite page.

And, finally, the parts image from Pentair: