1 tsp per gallon, and in your case i would recommend using from here on out if you have cut nutes already. are the roots slimy too? if your roots are getting slimy or there is a visible indication then you may as well go ahead and chop it.
last time i got root rot it basically killed all the fan leaves and stunted the plants growth
Is your room getting plenty of air movement? also, cloudy trichs is what I look for. Amber is the degration of Thc. Try flushing without the CarbLoad. I use it and love it, but when they are done, just ph'd water is chill.