Plants are great for smaller ponds, but for ponds 500 gallons and
up,definately invest in a UV sterilzer...They work extremely well, and will
keep your water 'green free' allyear long.

It will cost well over a hundred dollars for a uv sterilizer....I don't know
where you get your info....uness maybe you sell uv's. I run no
mechanical filters at all....just a couple of pumps into veggie filters. you
can see the bottom in all my ponds...from the smallest goldfish pond that is
2,500 gallons to the koi pond which is 3 1/2 feet deep and holds holds 13,000
gallons. Some of my koi are over 24 inches and I have a catfish in there that
is over 30 inches.....There is no algea....ALL due to having lots of plants
Another added bonus is that the veggie filters look just like small
ponds...because that is what they are. I have hundreds of water iris among
other things in them...and when the iris bloom it is a breathtaking
sight.....what does your uv look like? Jerri

http://www.fringeweb.com/Ponds/JerrisPond