Answer: It is normal for a new pond to change color at first. Pleae don't panic and don't drain it or start over. It will take time to establish a healthy balance in your pond. Also, in spring when there are temperature changes you will usually see an algae bloom for a little while, then once the temperatures settle it will dissipate. In a healthy pond the water is fairly clear but not quite like tap water -- you will not be able to see more than a foot or two down into it.
You need to have a variety of plants in your pond, they will help keep the water clear. The use up the nutrients and outcompete the algae, they also help shade the water which reduces algae. You will need enough to cover about two thirds of the surface area (water lilies are great for this job), and some underwater plants to help oxygenate the water (anacharis is an example, these are usually sold in bundles), and possible also some bog or margin plants.
Also, you need to be careful not to overfeed the fish. Give them what they can eat in just a few minutes once or maybe twice a day and that is enough. Excess fish food and fish waste will foul the water and fuel algae growth in a hurry.
If you want to try to clear it faster, you can try using a mesh bag or little bundle of barley straw. This is carried by many water garden suppliers.
As far as the larvae you are seeing, just add some so-called mosquito dunks. These are little floating disks of Bt. Your pond supplier should have them. Follow the directions on the label. They work great at controlling mosquitoes. Mark your calendar as to when to add them, you have to do it periodically.
Enjoy your pond!
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