I have a 27' round AGP and just replaced my old 20' Cooper Industries sandfilter and 1.5 hp Astral pump. Both were ancient and came with the house, and I constantly had pool problems. Tonight I put in a new Hayward package that came with their ProSeries S210T sand filter (21") and a 1.5 HP Power-Flo Matrix pump. The filter and pump are on a slab about 3 feet from the pool, so "head feet", as I understand it, is very minimal. Everthing is up and running beautifully, EXCEPT...there seems to be so much pressure from the filter (Hayward Vari-Flo valve) to the return jet that the hose (a think a 5 or 6 foot corrugated flex hose that came with the filter) is vibrating on the filter setting. There aren't any bubbles on the pool side from the return eye, but i do worry that the hose is "jiggling" a bit. The technical specs for the sand filter list the max working pressure (whatever that is) at 44 psi. The "pump output" listed on the Hayward site for my pump is 91 gpm at 10 "head feet" (the lowest measurement) and doesn't get to 44 gpm until around 45 head feet. The 21' filter circulates 21,120 gals in 8 hours; the 18' was just over 16k. So i am fairly sure the filter is the right size for my pool, (17,176 gals) and I have read that any AGP over 24' should have a 1.5 hp pump. Plus, it was a package, so i am assuming they sized the pump appropriately. Finally..here is the question: Should I worry that the return hose is vibrating? Do I need to install a flow meter? Or maybe a valve to adjust the output? I really appreciate any advise. I have been reading the forums here almost non-stop since i found you 2 days ago. Thanks!