I added a small pot with some lava rock, cut up pool noodles to my deck pond. The pump does 325 gallons per hour, basic tetra pond pump. The deck pond does not circulate except when the stream is running, which is on a timer.
With this add, the algae build up has gone away. There are two black gf in there that got there, probably as eggs, managed to survive being frozen over winter and two green frogs, snails and the normal pond critters.
All I did was tip it slightly so the water spilled over one edge, it is in the pond. The water flows between the two parts of the pond. There is even a fish in the 10 inch deep pond, no clue how it survived this winter.
I used a old piece of garden hose to bring the water from the pump to the pot, total investment, around 50 bucks. (Bought a matala filter for the pump, that was the highest cost)