I have had my two ponds for about two years now and have always worried about over-stocking. Between the two pool which are joined by a channel I estimate to have a volunm of 1750 gallon which equate to about 8100 lts, thats if my calc's are right. At present I have 2 Koi approx 8", 2 Grass carp approx 10" long, 2 Green Tench 10", 15 Goldfish approx 8" and the rest 11 approx 4"
I have 4500 gallons which equates to twice the size of yours and a bit more. Dont like to brag but I have nearly 100 koi approx 3-15". I was thinking that an inch per gallon was the old rate of convertion to fish so you can add a lot more if you want. Those two bioforce filters once built up can only be superceded by a sand pressure filter or a vortex on the front. to get up to stocking rate.dont forget they grow rapidly. Nice setup by the way regards www.fishkeepingsupplies.com Aquarium and Fish Supply Tropical