I think I have nute lock out help!!!

Been doing my ec @ 1.7 but within 5 days it's gone up to 2.1 any ideas or what I have done wrong

Too little N.

Could be but the young leaves are dark green and the older virtually dying going yellow and rust spots

when in doubt flush the plant. Its good for it.

No pics?

Answer is almost always to flush... Want to get fancy then make a tea.

I've only just finished flushing well a week ago and using oxy plus. I have a laptop now so I'll try to put up some pics

Did you check your ec before and after the last flush ?