Im a newbie in this hobby and need helps....Here is some pictures of my pond.....

currently residing inside the pond is:-
15 Patin (?)
5 Puyu (?)
10 Lampam Sungai (tinfoil barb)
15 Jelawat (?)
6 Kelah Hijau (mahseer?)
5 Temalin (?)
3 Kaloi Putih (White Giant Guorami)
2 Kaloi Sabah (Red Tail Giant Guorami)
15 Koi
5 Bandaraya (sucker fish?)
10- Keli Putih (?) (i think my arowana have make a dinner out of them)
and 1 Silver Arowana...

My filteration system i find it basic with sponge filter and coral in a 4 x 2 x 1 tank......the pond is around 10 x 3 x 2.5 (gallon? litre? i donno how to calculate).....

the problem is the water become too cloudy every two weeks.....i feed my fishes with palletes 3 times a day 6 in the morning, 3 in the afternoon and 11 at night (my fav feeding time since the fishes tend to be less shy at night). Everytime i change the water i just put 2 bottles of anti-clorin, 3 packets of salts, and halve bottle of aquabac (those good bacteria thinggy)....it will be crystal clear for the next 7 days but then its start get murky then end of another 7 days its practically filthy....mind u i washed my filter every 3 days....

so any sugestion?