Organic nutrients usually are broken down by the mycorrhizae in the soil. If in water, you really can't have mycorrhizae (they would drown).
Now base on that, I know NFTG does suggest it can be used in a water-based system. I have read people say it doesn't work well.
I'm sure some of the more experienced soil nutrient guys may have another opinion or information I know nothing about. I believe they will say to be effective you need mycorrhizae, and water somewhat prevents their longevity.
All based on research, no practical experience here.
Really? I've been using it in my dwc and it seemed every day I was having some kind of problem. Every thing settling to the bottom, PH spiking really high, discoloration on new growth. I use primo filtered water so I didn't see that being it. Then a buddy sent me a message about using organic store bought nutes causing issues in hydroponic. So I read up on the nutes.