the whole point of flushing is too rid the plant of nutes and toxins, your plant omit toxins in the water as a discharge...I think that is how it goes. Just adding something might work, but in my h.o., you just wasted nutes; And you don't know what's in there. You see, only with a fresh batch of nutes, will You really know what you got.

If you think you are wasting money...Do what I do. Think of how much that 'sakoweed' is gonna cost, if you lose'em.

I think you will find that any experienced grower will tell you; In Hydro if you are having nutrient or res problems....Emergency...
Danger, Will Robinson!, FLUSHFLUSHFLUSHFLUSH...What about the Epsom salts you added? Did you really need that in your res? It's like
fixing your car's electrical system...1 part at a time. Goodluck lw