HELP! What is this please?

Hi all,
I came home to find that my plants lower leaves had yellowed significantly. I've been using Sensi Bloom A+B if that helps and its currently at 21 days.
(Auto Bubble).

this is happening because the bottom leafs are not receiving any light and possibly a nitrogen deficiency. if they continue to get worse(bottom leafs only) i would just cut them off.
also try using a foliar spray called Optic Foliar.....or you can foliar spray some Cal-Mag......i buy these product from http://monstergardens.com/index.php?route=common/home

dude.. showing one leaf is not enough what exact npk are you using? how often do you water? probably you have N def. Do the leaves drop easily? do you have any ca mg supplement?

Hey, thanks for the reply's part A is 3-0-0 and part B is 2-4-8. The leaves on the other side are exactly the same (two single leaves which i took off and two of the bigger 3 leaves). The leaves feel firm and higher up the leaves are all nice and green. Cheers guys

Here's a pic of the light it's under (125w 2700k cfl)

i would say, you need to mix 3:1 ratio a+b. npk ratio of 3-1-2(12-4-8 ) you are looking for. that can keep you through out the entire grow. you did not say how much are u feeding now. your aim is to save foliage throughout the grow. so probably u need to increase be 2-3 ml per liter.. depends ofc on what are u feeding now.. also you will need some camg boost quite soon, make sure ull get it and start adding it with every feed.

oh wait, google gives me sensi a b grow npk listing, i see those have secondary and trace elements in their mix, so camg boost might be not needed
anyway i heard only bad things about AN. how they sell ripoff snake oil

Oh sorry i was using 2.5ml of each (a+b) per litre. It says it should be 4ml per litre of each but i didn't want to risk burning it as i've not been feeding very long.

ahh really :/? what nutes would you suggest? i've seen biobizz at a decent price. I'm in the UK btw.

i would increase only grow, you need N, high p will just lock out ca and some other elements. you did good for giving lower levels, its just that you slightly missed the time to increase it. give like 6-8ml and try to make n and k levels higher than p. cause if it appeared on lower leaves, quite soon it will affect higher ones, and higher...
good luck!

Okay thanks man, will do! Cheers for the help!

i was looking for dyna gro 3 products. dyna-gro folliage pro, mag-pro and pro-tekt in europe. the only distributor is in uk listed on dynagro site that sells them, and for quite cheap, but delivery to nl is 18 pounds lol... while ferts 3x 8oz cost 18 pounds in total. i would not suggest switching now, since u paid a lot probably for AN, just use it if it does the job finish with it, if not u can always order. i use biobizz biogrow together with aptus camg boost and some gk sea weed, does the job so far but after i will finish it, i will be ordering dynagro cause it is so much more complete.. 3 bottles all you could need in ur entire grow...

Okay thanks, I will defiantly consider buying them then after i'm done with what I've currently got! Cheers again dude!