at work we have a pond that is spring fed and covered with green algea and duck weed how can i get rid of this

Question

i have put some grass eating carp in it but nothing is happening the pond (small lake) is about 100ft wide and 200ft long

Answer 1

You need more "desireable" plants to compete for the nitrates in the water than are currently just feeding the algae. Fish waste, dead leaves, insect larvae, etc., decay and create ammonia. There are bacteria that "eat" the ammonia and convert it into nitrites, and a different type of bacteria that converts the nitrITES into nitrATES. Nitrates are essentially the same thing as fertilizer. So, if you put some heavy feeders in the pond such as water iris and/or water lillies, they will compete with the algae (which are basically just little one-celled plants) for the available nitrates in the water.

Fewer nitrates equals a better habitat for the grass carp, too (ammonia and nitrites are deadly for them, but they can handle the nitrates up to around 20-30 ppm). Grass carp will eat the duck weed, but may not be able to keep up with how rapidly it reproduces. Making fewer nitrates available to nourish the duckweed (again, by them being absorbed by adding "desireable" plants) should help slow down the reproduction rate of the duckweed and perhaps let the carp have a chance to get and stay on top of it.

Basically, you are trying to create an artificial ecosystem, and it may take a little bit of "experimenting" and some time to get the balance down just right.

There ARE algacides you can add to the water, but they will kill ALL plant life, and your grass carp would eventually die, too. Plus, when the algacide wore off, your algae problem would come back with a vengeance.

Hope this helps - good luck!!

Answer 2

You need an aerator, or something to introduce oxygen into the water. Something to stir the water up and get more oxygen into it, that will get rid of the algae.

Answer 3

have you read this:

http://www.ngpc.state.ne.us/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=2;t=013465