Hpw do i calculate how many gallons my pond is

[PS3]

when we built the pond the guy told my dad it would be 1000 gallons
but i think its more then that.. its oval 8 feet long and about 8 feet wide
and about 3 feet deep give or take a few inches
.

 

[DoDad]

http://www.gardenponds.com/Pondcalculators.htm

 

[PS3]

ok thanks my pond gallons is 1125 gallons
recommomd filter size 1139
pimp size 563

so will the 3200 laguna pressure filter and 2000 gp be ok for me