The more plant life in your pond the less algae you will have. Aquatic plants use up the nutrient in the water that feeds the algae, add oxygen and shade the water from the sun over the growing season therefore starving out algae. Algae is a plant too and naturally grows in water where it gets the right conditions just as weeds do in our gardens. The idea is to plant out your pond with the plants you prefer which is not algae!
Beneficial bacteria in your pond will eat algae so it is an important addition. This occurs naturally in rivers, streams and billabongs. Man-made ponds work best when we try to replicate nature. Oxygen from plants and good water flow, nutrient for aquatic plants and beneficial bacteria to consume, all exist in nature and are what a balanced eco-system needs for water cleanliness and clarity.
In order for your pond to have the best water clarity all these things need to be taken into consideration. If you have issues with water clarity one of these parts of the puzzle need attention.
Have you enough aquatic plants?
Do you need to add beneficial bacteria?
Is your pond very shallow?
Have you been topping up your pond with tap water too regularly and adding fresh nutrient to feed the aglae?
Have you been using algaecides which do harm your water clarity in the long run no matter what they say on the pack!
Have you been overfeeding your fish allowing the excess food to fall to the bottom and rot?
What fertilizes have you been using in the garden surrounding the pond and are they leaching into the pond?
What fertilizers and potting medium have you been using for your aquatic plants?
Is there a lot of leaf debris in your pond?
Have you got too many fish?
So many questions and so many answers to the puzzle!