Don't know where youre at but here, we can call the game and fish people and they'll send someone out to do a pond study. From there they can give you ideas that will work alongside the the goal of the pond, be it a livestock water source or fishing pond or whatever. And it's free here too, no charge. May be different in other states. BUt, it's worth calling them for info.
someone mentioned water lillies. Mmmm, again, don't know where you are at but if we put lillies in a pond here, they completely take over the entire pond in under a year. Of course it's dependend on depth as they don't live in water deeper than about 4 or 5 foot deep but if it's a regular "farm pond" like every piece of ground has on it in this area, lillies will completely kill everything else. Fish and all. That's why I suggested called the fish and wildlife people, as they'll give you a better idea what to use for the algae. It may not be "algae", it may be duckweed. Had a pond at the old house, and duckweed took it over. We were told to put some lillies in, which we did, and in under a year's time the lillies completely wiped EVERYTHING out (except themselves). Local lake, the fish & wildlife people did the same thing and it's a 6700 acre lake, which in the summer was maybe 1000 acres of usable water, the rest was lillies. They've actually completely dewatered the entire lake and are rehabbing it as we speak-a HUGE undertaking. Boats could not navigate without getting 'plugged up' with lillies. They'd keep the water cooler than usual in late spring but as the water temp warmed, they'd act like a greenhouse, and water temp would get up into the 90's-largemouth bass in the shallower areas would die off, as would the crappie and about everything else but alligators, some gars, one species of bullhead, and snakeheads. Then the coons skunks possums birds and CATS would gorge themselves on the carcasses. You can imagine the stench.