I would suggest getting a "native" fish first. Some type of brim/perch which could be caught from a pond/stream nearby.
Then after your sure it's alive and well, you can use this as they live off of the algae that makes water green.
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The purpose of the brim is to insure that there are no smaller type fish in there like gambusia which eat those Daphnia.
The brim/perch should be either a blue gill or an orange bellied(often called a pumpkin seed) as they eat floating fish food.
Some of the others don't eat anything but live food.
That colony of Daphnia will multiply till it consumes the algae and then die off till they are in proportion with just enough
to keep the water clear. This along/w a handfull of floating hortworth which you will need to cut some out once in a while
will keep it clear as a bell but take a little time to balance off.
Another trick I've found that works on particles as opposed to algae is to place a fence(not metal) around the pump intake
and put the hortworth in that. It limits where in the pond the plants grow, the plants don't grow all the way to the bottom
for lack of light at the bottom of them, but do filter the water for you.