If you use the GH go with the lucas formula. 1 part micro 2 parts bloom. It does very well for me. It can be used the whole grow. I have no problems. I hope you have EC or TDS meter, then you can practice max out on nutes. I don't use anything to flush R/O for the last week. Read the directions or search on the net. It most likely will be for the last 3 to 5 days.