Contact and wouldn't worry about it effecting an algae bloom. I will be using some soon in my yellow perch fry production pond to kill filamentous algae but not effect the algae bloom.

I tried the regular Green Clean itself. I think the filamentous algae laughed at it just like it does the Cutrine Plus in my very very hard water.

Last edited by Cecil Baird1; 04/08/13 05:46 PM.
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.