I have a 7,200 gallon in-ground fiberglass pool (12x20x4). There is 2"
PVC plumbing to the pump (Hayward SP3020EE). The pump has a 2 HP motor.
There is 1 1/2" PVC plumbing from the pump to the filter (Hayward
C1100). The exit plumbing on the filter is 1 1/12" PVC which goes back
to the pool. I acquired the pool and equipment used almost 6 years ago.
The base of the filter system is now leaking and needs to be replaced.
Based on the information I am finding around on the internet, I could
downgrade to a C-250 and I would still be over the minimum requirement
for a 7,200 gallon pool. The only thing that worries me is if there
would be too much pressure from the pump for a smaller filter system. I
have asked several people working at pool stores in the area. As soon
as I let on that I currently have the C-1100, they start salivating and
assure me that I should replace the equipment with at least the same
size if not bigger. But I don't get a good feeling that their
recommendations are based on something other than greed. Is there
anyone out there that really understands the water pressure involved
that can verify if a 2 HP motor will really cause too much pressure for
the smaller filter system?

Please Advise,
Mr. Boning