I've put plants in the bathtub before and just flushed with a shower head the kind on a hose. When I saw the color of the junk coming out, like dark orange milky crap flushing out, that's when I just filled the tub and started to ebb and flow the pots to flush them real good by just setting the pot in the tub picking it up and repeating a bunch, then drained the tub and flushed with the shower head again. Not sure why it was so nasty in those pots. Fermented roots maybe, I don't know. That was for a grow when I used Vermifire soil and the full line of Foxfarm nutes, as well as molasses, CalMag+, bontanicare ph up/down, RO water, and I'm probably forgetting what else. If its real bad like that a good product to use would be Cannazym, a enzym suppliment that will eat dead roots so the dead roots don't ferment, cause molds or disease and the such. You could also use a product such as Dark Energy or Big Bud which are Amino supplements. Cannabis is a c3 plant and can only use L amino's or left handed, left spinning amino acid's. L-Amino's have a chelate effect on nutes which make it easier for the plant to feed, this helps prevent nute lockout. Which nute lock out is one of the reasons to flush. Example being that when you feed a plant maybe something that is NPK 2 1 1 every feeding. Then over time the plant might use up all of the P and K but only 1 part of N, so then you feed again NPK 2 1 1. This time the same thing the plant uses up 1 1 1 of each. Over time that left over 1 part of N for example can build up as salts. This N buildup can lock out the P and K or something else. So you would flush to rid the excess N and salt build up. If you run a L-Amino supplement that will chelate nutes, this will help prevent nute lock out. So seeing your perdicament with the scrog setup, I would recommend Dark Energy or Big Bud. Maybe even some Cannazym as precaution so if there is any issues such as fermented roots the enzymes will take care of that.
