Is this mag def

Halfway through week 4 (25 days) can't quite put my finger on it been giving them cal/mag but still the leaves continue to yellow.i no I should expect some yellowing in flower but no as much as it has been!any ideas?

Looks like she's too low on nitrogen. The plant needs nitrogen at all stages just not nearly as much during flower as during veg.

Nitrogen is a mobile nutrient. Your plant is using nitrogen stored in the fan leaves to form buds. Should start low and progress up the plant through flowering.

This is good.

Adding too much nitrogen in flower makes for dark green harsh buds.

Thx guys but I was concerned about the amount of yellowing for only 3 1/2 weeks in flower.i have been giving them some grow only 1ml but still IMO to much yellowing.could a little Epsom b in order or should the 1ml of cal/mag I've been giving them have covered the mag def if any?

I'm not seeing any Mag deficiency. You're right, It's too much yellowing for only 3 1/2 weeks flower. If this is only one leaf I'd watch it but do nothing more. If it is spreading add some N fertilizer. If all you have is grow then use that at half the recommended dosage for a couple of feedings and watch the leaves. If they are getting enough at that point they should slowly get their green color back. If not add a little more a repeat. You can also mix urine at about a 20/1 ratio with water and use that for a few feedings. Good luck.

Urine really? I have been giving them small doses of grow but it's not making ony diff and yes all the leaves up to nearly three quarters the way up r going like this.i feed my plant every 2to 3 days water and minimal nuites I don't miss a feeding eg people say water feed water feed .i no this is a rhetorical question but could this b anything to do with it.