I'll just throw this out there but too much CO2 in a sealed room could spell trouble, you're probably using guages but just throwin it out there.

It kind of sounds like you're over feeding them and you'll need to do a few flushes then I'd stick to straight water and maybe add superthrive for about a week. Try diluting your nutrients with about 50% more water then you have been using. I fried six beautiful plants once and have always been a little over cautious ever since.