I'm trying to control watermeal on a 3.5 acre pond with bass and bluegill. I'm reluctant to use chemicals. I was told by a fish source that Japanese koi would control watermeal by eating it and reducing nitrates in the water. Can anyone verify any results?

Also I've read tilapia may work but will not survive the INDIANA winters. Any experiences?

Lastly, it seams the only proven option is sonar. What is the minimum concentration that gives results?

Thanks in advance.

Phil I have not heard that Koi can solve your watermeal problem before. You have a large pond and even if the Koi did eat the watermeal it would keep multiplying over the areas feasted on. Sorry to say Fluridone is your ownly option until something else comes along. I used to work for the manufacturer of Sonar and would prescribe max rates for watermeal. 90 ppb. Which means if you had a 3.5 acre pond with an average depth of 5 feet you would need 136 ounces of Sonar. Could get pricey and would take out the rest of your vegetation.

Eddie is right. The only way to get control would be to use a fluridone product (Sonar). It can get to be expensive, however. Treat in early spring when the watermeal first starts to show it's ugly head.
Good luck!

PhilR :

There is a new product called habitat that Kelly Duffie has discussed on the fourm. You can search for references. I checked the label and it lists duckweed and many other pond and non-pond plants . It does not list watermeal but watermeal is a little like duckweed . I have used habitat with good results on pondweed and it is not on the label either. Prior to this use I contacted the manu. rep. and he checked with a prof at LSU who worked on its development and he said it would work and would be ok to use. See below.

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=14;t=000155

Maybe Kelly will post on this later.

The cost was about $70 a quart which will treat about 1 acre with a mid strength application.I don't know if this will work for you but it would be worth checking on. As with all products read the label and use correctly. This product will kill many pond and non-pond plants including many trees if sprayed on ground over or near roots. ewest