Some states will not allow the use of a submersible pump in a lake. Electrocution concerns is the reason they give. A good shallow well jet pump is an easy choice. There is one kind of sprinkler head that is just about algae-proof, and that's the impact head. If you have concerns about cruddy water, then impact heads should be considered. If you can filter the water enough for it to be clear, than gear drive heads like a Hunter PGP will also be effective. Same idea with valves. If I can filter the water through a 100 mesh screen, I can use clean water valves. If I can't clean the water enough, then more expensive zone valves are needed, to work reliably with dirtier water.