I bought a 50lb bag of Copper Sulfate crystals/powder and would like to begin treating a 4 acre lake that was freshly dug last summer. I'm starting to see some green stuff around the perimeter and wanted to get ahead of it. The landscaper that I purchased it from suggested that I pour about 10lbs inside of a pillow case and then tie it off with a rope and drag it around the perimeter of the lake which would allow it to diffuse into the water. Alternatively, I've read that it should be mixed into a tank sprayer with hot water and sprayed around the lake. Some say they sprinkle the crystals or powder with a broadcast spreader or by hand sprinkling. Just wondering if there is a "best" method to this before I give it a go this weekend.

The "best" way to apply it is to read and follow the label, dissolving the correct amount in water and spraying it on the area that you want to treat. You have to read the label and use it correctly, it is toxic to fish if used incorrectly.

I found a copy of the label on-line, here it is, follow the directions. Depending on the type of algae that you have, you have to apply it so it has a concentration of between 1/4 and 2 PPB.

https://www.domyown.com/msds/Crystal_Copper.pdf

If it's medium or large granules, then it's made to drag around in a burlap sack. If it's the fine Copper Sulfate, then it's made to be dissolved in water and sprayed. *make sure you triple rinse out your sprayer or the copper will eat the insides out relatively quickly if you put it away without cleaning it.*

Be sure you need to do so first. New ponds should not need treatment. Search on the Forum for info on CUSO4 before use. It can cause long term problems.

CuSO4 is a contact killer meaning it has to be placed in contact with the algae to 'kill' it. If your algae is mainly along the shoreline no need to treat the whole pond volume - just the shoreline area. If most of the algae is on the surface use it as a spray. If it is mainly underwater dragging in a bag dispersing dissolved CuSO4 is effective. IMO do not use the entire calculated amount in the drag bag all at once. Too much copper dissolves all at once and too quickly and thus does not treat lots of shoreline. Divide calculated amount it into smaller lots and drag and dissolve each lot separately. Thus less copper is used or needed.

Every ounce that you apply will stay as a bound compound the pond sediment forever or until the sediment is removed. Chemically bound copper carbonate does not break down nor dissipate. Copper is a heavy metal and a stable element compound in the environment, thus it can accumulate in the pond bottom over time as it is repeatedly used .

Thanks for the tips guys. So from what I read, Copper Sulfate is by far the least expensive of all algae treatments and I bought several 50lb bags before I researched a lot. From what I've read, Copper Sulfate breaks down the algae and produces sulfate in that process which can feed additional algae. Not ideal. I have no desired fish yet, so that's not a problem. What else do you suggest I use instead of copper sulfate then? The lake is currently only about a 3rd full.

Note, I plan at some point in the future to add lake aerators, but that will be a few years out as I'm unable to afford that at the time. I would like to stay ahead of any growth problems by keeping it clean. Your suggestions are appreciated!

Alternatives to copper sulfate will depend on your pond management philosophy. Chemical or natural or combination of both.

From our Common Pond Q&A Achives
https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=92633#Post92633

Leached nutrients from within the pond basin and water shed nutrients accumulating in the pond are feeding the algae. The bare pond bottom without water would grow lots and lots of terrestrial weeds same as bare land does. Once nutrients are in the pond, nutrients are used and usually recycled for new growths. Balance of nutrients mainly N and P determine who is growing in terms of FA or planktonic algae or higher vegetation. Removal of nutrients to reduce fertility is the best approach but not the easiest approach. Harvest the crop to reduce pond nutrient load. Farmers have to fertilize due to harvest activities.

The bigger the pond the more work intense harvest becomes. Just killing the crop does nothing to reduce causative agents of nutrients. As the pond ages submerged weeds invade the pond or beneficial plants are added. These plants heavily compete with algae to sometimes make algae, especially filamentous algae (FA), a minor growth component. Nature ALWAYS operates by various competition factors among the life forms - be it plants or animals.

Do not rely on aeration to reduce the amount of FA because aeration does not eliminate nutrients although sometimes it helps adjust the nutrient balances. In my experience many many ponds that have good aeration have huge amounts of 'algae' which should tell you something about aeration and algae..