I looked it up. Brother you gotta be the most read person on the planet! No otter spraint!Insect frass, worm castings, bat guano (don't forget otter spraint...sorry @StoneOtter!). So many fancy names for excrement.
They really do!
I would recommend against that, particularly with a synthetic nute grow. Runoff is one of the ways to keep the old nutes from building up in the substrate.