Another note: my brother used fluridone in his pond to the tune of about $4000. Killed all the duckweed for about one month, then came back over next two years heavier than ever. I have spent about $450 on my pond so far including buying the 15 gallon sprayer. Have found great suppliers for diquat, copper and pond dye at very economical prices. If you are interested I can email you those websites,
