Millwoodva, other options are cutrine plus, tilapia, and maybe copper sulphate since fish are not involved. If I understand correctly, you have a stream that feeds the pond continually so there is always flow through with new water entering and then exiting the pond? If so, any type of chemical application will only be temporary as it would be flushed through fairly quickly? One could place a bag of copper sulphate crytals at the top of the stream and let the crystals disolve slowley over a day, the larger crystal do disolve more slowly. Normally I would recommend avoiding copper sulphate as it will kill the invertabrates that make up the base of the food chain for the fish too. It is also cosidered a heavy metal. It is also relatively expensive too compared to Clorox. Here in the midwest copper sulphate is used to keep the water tanks for livestock clean and to keep irrigation canels clean of filmentuous algea or other types of vegetation. 50# bags are available at most of the local Coops and the last time I checked copper sulphate ran $2.50 to $3.00 a lb. \:\(