Well, obviously pyre-bomb the box between cycles. I've had good results w/ abamectin drenches, but you want to flush pretty hard, pretty quickly. No idea how abamectin will interact w/ coco, but I don't see any obv. issues, long as you rinse it out 15 minutes later. Drench by hand, not thru irrigation system- looking for momentary oversaturation. Divert run-off from drench and rinses away from res, if he recircs. Aerate run-off for 24 hours to oxidize before disposal. Pyrethrin drench should work as well, but I've seen weird phytotoxicity .

Bag up and throw away used media after harvest, unless you want to heat-sterilize till bone dry.

Mom's are probabley affected too- regular spray program alternating neem/safer/pyrethrin every 3-5 days for like a month ( beware of waxy build-up) or abamectin/ safer tank mix weekly for 4 weeks, physical barriers over media to prevent larval burrowing. Remove tissue if any sign of larval feeding.

The bitch is that only the adult can be contact sprayed- to get the leaf and flower eating larva, you have to use a translaminar, and whatever your poison of choice for the subterraenean stages may be, you have to deliver it in in-vitro.

Slick- ever tried beneficial nematodes delivered thru your irrigation system? Can be quite effective, and they're the easiest bio-control to manage.