DE filter backwash (newbie)

[hikernut]

Hi,

I just bought a home that has an in-ground pool with a Hayward DE filter (60 sq ft filter surface). 2hp Hayward single-speed pump. By my yardstick measurements, pool volume is approx 25,000 gallons. The home is seven years old, and I believe the pool equipment is roughly the same age.

I backwashed for the first time today. Pressure reading prior to backwash was 22 psi. I backwashed for about 2.5 minutes (until it looked like the water was relatively clear). The filter calls for 7.5 lbs of DE. The home's previous owner told me he usually added 5 lbs of DE after a backwash, so that's what I did this time. Pressure reading after backwash is 18 psi.

Am I in the ballpark here? I was expecting a bigger drop in pressure after the backwash, but I have no prior experience as a pool owner.

Thanks,

hikernut