There are other agents you can get that assist in the removal of nutrients from the plant as well.
FloraKleen by General Hydroponics
Final Phase and Drip Clean are just a few
They cost less money than nutes and you only need use them the last few days before chopping
They break the bond between the plant and nutes.
The nutes can build up in your reservoir tho so watch the PPM and if it gets to high empty and refill.
Plain water works very well too, just this stuff gets chemicals out faster.
I use Flora Kleen for 3 days then plain Distilled water till I'm ready to cut em down