This is from Practical Fishkeeping Magazine,
"As a general rule of thumb you need to allow for a pond which recieves at least half a days worth of sunlight, or more than 10 watts of UV light per 1000 gal of water - so on a 5000-gal pond, you would need 50 watts of UV, but most models (not all!) come in sizes of 4, 6, 8, 15, 25, 30, 55, so you would be best opting for a 55 watt unit, which would cost around 110 pounds, as it's better to be over than under."
So for your pond, I would get 60 watts. This is because there would be next to no shade and its out in full sun, thus needs stronger UV to kill the faster growing algae. Also you dont know how many gallons exactly, so I'd rather be way over then under.
"As a general rule of thumb you need to allow for a pond which recieves at least half a days worth of sunlight, or more than 10 watts of UV light per 1000 gal of water - so on a 5000-gal pond, you would need 50 watts of UV, but most models (not all!) come in sizes of 4, 6, 8, 15, 25, 30, 55, so you would be best opting for a 55 watt unit, which would cost around 110 pounds, as it's better to be over than under."
So for your pond, I would get 60 watts. This is because there would be next to no shade and its out in full sun, thus needs stronger UV to kill the faster growing algae. Also you dont know how many gallons exactly, so I'd rather be way over then under.
