Unused Nutrient Solution?

I just started a coco grow and have been feeding about 200ppm for the first two weeks. My next feeding I am going to up the ppm to about 500 ppm. What should I do with the unused 200ppm solution? I still have around a half a gallon left.

add more nutrients to it until it is 500ppm.

Or discard. It depends on how much those nutrients cost to you. cn

Give it to a house plant or something.