Question for diesel guys

[Ratdog]

How do. Do you all know about how people put copper sulfate in ponds to kill alge. If so you will understand if I ask if there is a way to do that for stagnat tanks in the 500-600 galon range.
If you eer had a alge problem you understand preventing it from happening again is a priority.
So the next question is what adverse situitanals do you for seed for putting copper sulfate in diesel. As I wonder if it might not be good for old motors with da incress in sulfides in the low sulfer blends.
Next how is it that on land red diesel costs less than on the coast. I came to understand died fule was always at least a dollar cheeper than the highway clear kind.

Thanks and no I never put it in a tank yet. Jus looking for a pluss pluss solve for a problem I foresee could come up on my boat.