That’s all I can say about two of the IBCs. Two growbed/sumps are just fine, cleaned up now. The other growbed/sump used to have glue in it, it turns out. See the picture below – I ended up using the pressure washer at its highest setting and it was able to get the big parts out. After it dries out a bit, I may try sandpaper to see if it can get rid of the remaining glue bumps. The fish tank is a little different – rather than glue, it seems to be some sort of greasy gunk that does not seem to go away – there’s still a film on the inside. I may try the bleach and hot water approach that I’ve heard suggested as a good general approach… or I may look for a strong degreaser.