Shouldn't it be okay for the plants you don't spray it on? If in doubt, run it through a seperate biological filter first. I would think that this would step the nutrient level down a notch but still leave enough in it to make it work. Similar to the concept of letting fresh manure age a bit before composting it or adding directly to plants to avoid nitrogen burn, etc. I think....that might be a better way to go, or at least consider, and biological filters are typically low cost. But you would have to test the end water to see how much is actually being taken out. I don't know if it would work enough, or maybe even too much. Just a thought vs tabling the whole idea.