Ive had dealings with fish ponds before. What you need to do is balance your ecosystem. I don't recomend the algae killing chemicals. You should get all the following:
-regular fish, they control the numbers of the other animal life
-catfish or sucker fish, they eat algae and poo.
some kind of scavenger, though catfish will expand to fill that role. do not get crayfish, they destroy everything. I use freshwater prawn. they nibble bits of algae off everything, reproduce quickly, and are food for larger fish.
-tiny minnows, theyre a more mobile food source and plant growth controller
-aquatic snails, not "golden" snails, as they eat everything. regular aquatic snails will eat algae that grows on the side of the pond and not much else.
-plants that grow entirely underwater, like aquarium plants. food and oxygen source
-plants that grow partially in water and partially in air, like cat tails and water lilies, food source, oxygen source, and shade source. fish like shade sometimes.
-little bitty free floating plants. duckweed recomended. these grow more in the hot months, providing shade to keep your fish from overheating.
Don't bother with exact quantities of the living things, as they either die off or reproduce to fit the size of pond you have.