natural vs. chemical

So, it's a culture thing.

I live in Phoenix, AZ. So where most of y'all have to contend with
freezing winters, we have 110 degree summers.

What I've got:

homemade pond, rectangle, liner, half in and half above ground
two feet deep, 6x8 ft
700 gallons
anarchris and cambomba
two koi, two comets, one cichlid, some feeders, some minnows, guppies,
neon tetras, zebra danios - about 50 fish, most of them very small. The
cichlid's been thinning the ranks of the minnows, which is great.

I've had no problem with koi + plants. Has anyone else had sucess with
that combination?