My thinking was one approach would be to put it down early and but it will get diluted.
And once its frozen at those termperatures, I think its not practically possible to melt effectively. At best maybe make little holes around each pellet where the molar concentration is really high.
Even that won’t work. There is no molar concentration high enough to work at those temps. It will have to melt the ice and have the water sublimate before it all refreezes.