Hi Tom, Yes you can usually mark your calender when you treat with Cutrine as far as when you will need to do it again. As far as copper goes it is the safest one on the market. You may want to consider alternating treatments with something like BioSafe's GreenClean PRO ( 85% sodium carbonate peroxyhydrate aka hydrogen dioxide)You may find with extended Cutrine (or any copper)use that it will take a higher dose and more often as time goes on, most folks relate this to warmer water temps as the season progresses but I believe resistance builds. I have witnessed ponds that have used copper for the last 10-15 years and no amount of copper works on their algae any longer.Also keep in mind grass carp do not tolerate a lot of copper. Perhaps Bill C and or Kelly D can add to this post.We dont want to have you considered the "Southern Love Canal
" Good Luck Ted
