It is free draining, at that. That is what makes it so good, lots of oxygen to the roots!

I sometimes would add plain water till it ran out the bottom profusely, to be sure all the media was saturated and then went back an hour or two later with the water/DG-FP. Water the second time with the ferts very slowly, just enough to get a slight drainage.

Works great, but I only have 10-12 pots, and didn't mind spending the extra time, which was usually on the weekends early in the morning while I was drinking my morning coffee.