Quote Originally Posted by mrs.rainbow View Post
I have a 1.5 hp pump and a 16 inch filter( 100 lbs sand) and my pool runs right around 20,000 gallons. It did fine for 10 years
I always try to avoid arguing with success.

If you operated successfully for 10 years with a 16" filter, and now have the same pump, but with an 18" filter . . . it should work better than it did before. And, since it worked to your satisfaction before, it should be fine now.