Need to know when to flush?

[Jbum]

Here ya go.

To flush or not to flush or to flush

My plants are 45 days old. I have been giving them nutrients for about a month. Easy at first but up to full strength now. They are ak47 and super skunk auots and show no signs or stress. I use the trio but not in the seedling stages. How do you know if you have to flush or not? Do I need to flush at all? can I do it without sledgehammer? Thanks,