Tomorrow work get that other room sorted out ,I'm convinced that the two vents on the wall are perfectly working ,they may have a bit of a build up of rubbish from over yyear.But im gonna rip fronts off and replace them with the 4 inch duct connectors so i know there no chance of any insects getting in.I use a pair of our lasses stockings to put over end of duct to stop any insect no matter how small.The same thing is done with inlet ,its always worked in past - then seal it with foam.The next location will be done from scratch - so that's gonna be fun not - poly walls reflective sheeting around bottoms polly whole room really get both 600s in place ,and get table ready .So all been well tomorrow both should be done ,now plants are back at original place they should pick up .