Growth products has a soil amendment that I've been using for a few years called Essential plus 1-0-1. I use it on everthing from turf, ornamentals, veggies as well as my MJ. It's amazing stuff as well as Growth Products 2-3-2 biological fungicide. I use both from seed to to flower as well as a...
I use a mix of Fox farm ocean forest, master nursery bumper crop, coast of Maine lobster compost, coarse perlite, turface, coconut coir, sphagnum, and a wide array of organic fertilizer and amendments and let sit from fall til next spring!
You're not going to down your roots by having too much water depending on the amount of time submerged. yellowing of the leaves is natural during the end of the flowering process, but that droop is something underlying from a pump failure or something.