OK, I just did a google search on this topic, and I am even more confused now! Some people say the
media surface area should be 5% of pond surface, or 10%, or 1/3 or based on weight of all your koi, or,
or, or ......... YIKES!!!

Going by the weight of the fish (what they will grow to) is probably the
most accurate, since the amount of filtration will be reflected by fish
numbers & sizes. Back when we did our filter we were told 10% by gallon.
1500 gallon pond = 150 gallon filter (not counting the 55 gallon pump
chamber). This has worked well for us for over 7 years, but with 16 koi
and many of them 7 years old I've pushed the limit this year and have got
to cull the herd, it's either that or not feed them...ever. ( ~ jan

See my ponds and filter design:
http://users.owt.com/jjspond/

~Keep 'em Wet!~
Tri-Cities WA Zone 7a
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