havnt washed the res since i started, i change nutes every other week and top off every week. the nutes are B.C. boost, B.C. grow, B.C. bloom, thrive alive b-1 (red and green), awesome blossoms, magical, root 66, sugar daddy, all these are for veg and flower so i dont use all of them right now, i read elsewhere that the thrive alive red cause the roots to darken, ill post a pic later of the roots, technafloras recipe says to change nutes everyweek, i was just trying to make the nutes last by going every other week..........i only use 1/4 strength for the nutes I dont have a ppm meter so im just adjusting ph