Thanks for the tips guys
My water here is pretty soft- barely any Kh level at all, just in case it is overfertilsation I will give it a real good flushing to flush out any possible built up salts/and or fertliser.
Also the pot is topped off with largeish pebbles, so I'll take them out tommorow to see what the mix underneath is like.
It's actually in spike too
Damian.